F2-F: Remote Vibrational Spectroscopy Detection of Highly Energetic MaterialsAbstract — The objective of the ALERT F2-F component is to develop Remote Vibrational Spectros-copy in spectral and hyperspectral detection of highly energetic materials (HEM) and homemade ex-plosives (HME). The expected outcome of the project is to significantly improve the current state of development of vibrational standoff (SO) detection of HEM/HME in terms of range (target-observer distance), detection limits, discrimination capabilities and quantification studies of HEM/HME from interferents (background and matrices). During Year 4, significant improvements in the development of our remote Raman system resulted in measurements of 4-component mixtures (28 mixes) able to perform quantification studies of HEM in complex matrices at 10m. Low limits of detection studies are in progress by designing experiments in Chemometrics to perform the studies. Remote sensing based on infrared technologies was also developed further. A commercial system was modified by re-placing its source by a carborundum heater and the mid-IR (MIR) telescopes originally designed for atmospheric sensing have been replaced by ZnSe transmission lenses that focus the source beam on the target with significant area of interrogation (not point sensing) and high energy density. In addi-tion, other excitation sources are currently being explored.

I. PARTICIPANTS

Faculty/StaffName Title Institution Email Phone

Samuel P. Hernandez-Rivera

Prof. UPRM samuel.hernandez3@upr.edu 787-265-5404787-833-5839

Leonardo C. Pacheco Post-Doc UPRM pachecolc@yahoo.com 787-265-5458Students

Name Degree Pursued

Institution Email Intended Year of Graduation

Hilsamar Felix Ph.D. UPRM hilsamar@gmail.com 2012William Ortiz Ph.D. UPRM wortiz30@yahoo.es 2012Gloria M. Herrera Ph.D. UPRM Marceherra_s@yahoo.es 2012John R. Castro Ph.D. UPRM jhon.castro@upr.edu 2014Pedro M. Fierro-Mercado Ph.D. UPRM fierropm@yahoo.es 2012Jose L. Ruiz-Caballero Ph.D. UPRM jlruiz50@gmail.com 2013Nataly Galán-Freyle M.S. UPRM nataly.galan@upr.edu 2013Carlos Ortega Zúñiga M.S. UPRM carlos.ortega4@upr.edu 2013Luis A. Rosas-Diaz B.S. UPRM luis.rosas@upr.edu 2012Sandra N. Correa-Torres Ph.D. UPRM sandranataliac@yahoo.es 2012Amanda Figueroa-Navedo B.S. UPRM amanda.figueroa@upr.edu 2013Kevin LaBelle B.S. North. Essex C. C. klabz28@gmail.com 2014Brian Neaves B.S. Vanderbilt U.

Nashville, TNbrian.g.neaves@vanderbilt.edu 2013

II. PROJECT OVERVIEW AND SIGNIFICANCE

Vibrational spectroscopy has been continuously developing for sensing applications of HEM and HME as part of the University of Puerto Rico-Mayagüez F2-F component during the last 12 months. Research has covered applications in the near field (under the microscope: VIS or mid-IR) to remote sensing: 0.5 m (and closer) to 30 m (not limited by range: source – target distance). Synthesis, characterization and samples and standards preparation studies have also been conducted as part of the point detection (Raman and IR) and wide area detection (IR) studies.

A. State-of-the-ArtandTechnicalApproach

Rapid and precise identification of high explosives (HE), as well as homemade explosives (HME), is one of the central tasks of security and public safety personnel, particularly with the recent proliferation of improvised explosive devices and other explosives threats worldwide. Instruments that can be used in the field to rap-idly and accurately detect and identify explosives and their precursors should form part of checkpoint secu-rity stations in airports, seaports and government buildings. Infrared spectroscopy (IRS) in the mid-infrared (MIR) region has played an important role in the characterization of highly energetic materials through per-sistent characteristic signatures. These signatures can be universally used to detect these compounds from a distance. The merits and challenges for the technique to be applied outside the sample compartment include the following. Remote – The technique should be capable of detecting explosives at a distance under non-contact condi-tions (i.e., at distances from cm to m from the source).Universal – The technique should detect all types of explosives.Specific – The technique should be able to detect and identify explosives with relatively few false positives. This requirement suggests the use of spectroscopy. It should also be able to deal with samples contained in mixtures, a potential problem for spectroscopy.Rapid – The technique should be capable of providing results in a short time.Results of these works have been recently published in international conferences and peer-reviewed jour-nals. Two other papers will be submitted soon that will demonstrate pioneering work in applications of par-tial least squares in quantification analysis and principal component analysis coupled to linear discriminant analysis for identification/recognition. Papers presented at international conferences and published in peer-reviewed journals are by definition state-of-the-art in the particular field.

B. MajorContributions

1. SamplesandStandardsPreparation

Samples and standards preparation is at the center of any certification and validation program and is of utmost importance in evaluating the effectiveness of detection methodologies development. Understanding of surface-threat agent interactions contributes both to the characterization of the assessment and develop-ment of detection technologies. Basic information on the molecular nature of the interactions that lead to properties such as adhesion, attachment, and adsorption on different surfaces in contact with threat chemi-cals can also be assessed by implementing a robust program in standards and samples preparation. It is important to gather information on properties, such as which surfaces retain more threat chemical particles, measurement of the residence time of target molecules of threat agents deposited on the surface and the temperature dependence of adsorption-desorption processes, including the extreme conditions to which im-provised threat agents component can be subjected. Three methods have been developed for the preparation of homogeneous samples and standards of solid

particles and traces of HEM and HME deposited on surfaces. These specially prepared samples were used in experiments that require fine control of the distribution of analytes on the surface and the establishment of reliable standards that can support an instrument response validation program. Sample smearing (Fig. 1a), thermal inkjet (TIJ) sample deposition (Fig. 1b) and spin coating deposition (not discussed) have been used as excellent and relatively inexpensive methods for transferring explosives onto substrates: metals, glass, quartz, silicon, cardboard, filter paper and others [1-6]. Sample smearing preparation generally follows the preparation of a standard solution in a solvent, in which the test chemical is highly soluble. Briefly, a con-centrated stock solution of the analyte is prepared in the appropriate solvent. Dilutions are made to achieve the desired surface concentration after depositing 20 μL of the solution on the surface (an effective area of 46.3 cm2, a 3-cm width and 15.4-cm length). Finally, 20 μL of the solution is smeared over the surfaces in a single pass operation using a Teflon sheet that is inclined towards the right or left as shown in Fig. 1a. The resulting deposit is air-dried at room temperature for 10-15 min to allow the solvent to evaporate, and vibra-tional spectroscopy analysis is performed. Because the methodology is based on gravimetric procedures, the samples used as standards may be considered primary standards.TIJ technology, illustrated in Fig. 1b, offers several advantages compared to smearing deposition [7]. This method is not subject to human error and provides more uniform coverage. Moreover, the surface loading concentration can be varied by changing the numbers of passes delivered to the sample, the dispensing fre-quency, and the applied energy and pen architecture. Additionally, the method includes precise delivery of a number of droplets with well-characterized mass and concentration. Furthermore, only one solution need be used, avoiding dilutions that can increase the analytical errors caused by human intervention. In the thermal inkjet method, a thin film resistor superheats less than 0.5% of the fluid in the chamber to form a gas bubble. This bubble rapidly expands (in less than ten microseconds) and forces a drop to be ejected through the exit orifice. The samples were dispensed using an ImTech™ Imaging System, Corvallis, OR, model I-Jet 312S, (Fig. 1b) equipped with an HP™ model 51645a inkjet cartridge. Explosives solutions were placed into the inkjet cartridge, and the backpressure was set to three inches of water using an external backpressure controller. The solutions are then dispensed over SS plates using a zero dot spacing script (space between drops using HP inkjet) at a printing resolution of 600 dots per inch (dpi). Once the solvent evaporates, the spectra of the samples were collected under the same conditions as the background plates (blanks).Target HEM and HME studied were:1. high explosives: RDX, PETN, TNT, 2,4-DNT and HMX2. homemade explosives: TATP, HMTD, TMDD, ammonium nitrate, and urea nitrate3. mixtures of explosives: pentolite, ANFO4. explosives formulations: C4, SEMTEX-H

Fig. 1. Methods of transferring a solid sample onto substrates: (a) sample smearing; (b) Thermal InkJet deposition.

2.SynthesisandCharacterizationofExplosivesandMixtures

Due to the ALERT F2-F component location and its inability to access military grade explosives for vibrational spectroscopy based detection, the research, education and training group at UPRM has been steadily building its organic chemistry skills for synthesizing cyclic organic peroxides [8]: TATP, DADP, HMTD and TMDD; ali-phatic nitroexplosives: PETN (a poly-nitroester) and poly-nitramines: RDX and HMX. A new synthetic route for preparation of milligram amounts of DADP in purities exceeding 99.999% will soon be published [9]. The proposed synthetic scheme can be useful for preparing small amounts of the cyclic organic peroxide for fundamental characterization studies and for formulation of gas chromatography, high performance liq-uid chromatography characterization and mass spectrometry standards. Characterization studies include thermal analysis (thermo-gravimetric analysis, TGA and differential scanning calorimetry, DSC); magnetic resonance analysis (proton, 13C and two-dimensional nuclear magnetic resonance correlation spectroscopy, COSY-NMR); solid state vibrational spectroscopy analysis (Raman and FT-IR); gas chromatography (GC), high pressure liquid chromatography (HPLC) and GC-mass spectrometry (electron ionization, EI and Open-Air Chemical Ionization-MS using a JEOL Direct Analysis in Real Time (DART™). The work was accompanied by a theoretical computations comparison to TATP through optimized structures vibrational normal mode analy-sis and molecular electrostatic potential (MEP) contour map for DADP. Students are a huge asset of the UPRM effort. For example, Mr. Eduardo Espinosa, a doctoral candidate at UPRM, is the principal researcher involved in synthesis and characterization studies of cyclic organic perox-ides. He also worked on four important related projects:• “Non-Linear Fittings for Thermal Sublimation of Homemade Peroxide Explosives”, to be presented and

published as part of the 40th Annual Meeting of the North American Thermal Analysis Society (NA-TAS-2012)

• “Inhibition of the TATP synthesis from household products”. More tests have to be done before project completion, filling of recommendations and publishing of results.

• “Mechanism of formation of uncatalyzed acetone-peroxide reaction”. Slow, rate determining step is com-pletely characterized. Faster component still being worked on.

• “Mass spectroscopy and NMR characterization of TMDD and Isotopomers” in collaboration with John Dane and Robert Chip Cody of JEOL-USA, Peabody, MA.

Mr. Espinosa is currently at an internship (PhD requirement at Chemistry-UPRM) studying modeling through molecular mechanics, of crystallization of polymorphs of TATP. Very recently group members started the synthesis of mono, di- and tri-nitration of toluene, obtaining highly pure, milligram amounts of nitrotoluene (NT), 2,4-DNT and 2,4,6-TNT, thus completing the required HEM and HME required for near field and far field measurements. This effort began on June-2012, led by doctoral can-didate José L. Ruiz-Caballero. This work was sparked by a suggestion from Professors B. Weeks and L. Hope-Weeks (ALERT-TTU), to create a comprehensive program in thermal and spectroscopic characterization of neat, binary mixtures and ternary mixtures of HME with accelerating and decelerating compounds and with HEM. Results will be presented as part of NATAS-2012. Carlos Ortega, MS student is in charge of thermal analysis characterization of HEM-HME studies. He is assisted by two ALERT REU students.

3.NearFieldSensing

Highly sensitive substrates capable of use in SERS for detecting a hundred molecules or less were prepared via thermal inkjet technology. The silver films were prepared by printing silver nanoparticles (Ag NP) sus-pensions on quartz and other surfaces. The prepared substrates were characterized by UV-Vis spectroscopy, and the morphological evolution of the films was monitored by atomic force microscopy. Inhomogeneous coverage of the Ag NP was obtained for a single deposition, while a more uniform distribution of Ag NP was

obtained when the number of depositions increased. The SERS performance of the prepared substrates was evaluated using p-aminobenzenethiol (PABT) as a probe molecule (see Figure 2). Mr. Pedro M. Fierro-Merca-do has been responsible for the development of the methodology. A manuscript containing the salient results has been sent to Chemical Physics Letters [10]. SERS vibrational maps of substrates showed an increase in the number of hot spots attaining homogeneous distributions throughout the entire substrate surface after the addition of more Ag-NP layers. Statistical analysis of histograms obtained from vibrational maps of the analyte (PABT) adsorbed on the substrates pre-pared by 20 depositions of Ag NP shows that reproducibility of SERS intensities is about 8.9%. An invention disclosure has been filed as part of this work (See Figure 3).The surface enhancement factor was estimated to be 9.0 x1012, which is comparable to the substrates pre-pared using more sophisticated methodologies, such as lithographic techniques or vacuum deposition. De-tectable SERS signals were obtained with a good signal to noise ratio when only approximately 136 molecules were estimated to be in the interrogation area under the laser spot. This methodology is quite adaptable to a wide range of sensing platforms and analysis scenarios because it allows for the deposition of nanoparticles on nearly all substrates. SERS experiments were performed on highly energetic material molecules using a sensing platform fabricated by depositing gold nanoparticles on common lab filter paper (Whatman® Grade 1) using thermal inkjet technology. Figure 4 illustrates the proof-of-concept experiments performed using a low cost Agiltron Raman System RM-3000 (785 nm).The choice of paper as substrate for depositing plasmonic structures useful as possible SERS active substrates

Fig. 3 SERS vibrational mapping of vC-S peak intensities of PABT adsorbed on Ag NP films prepared by thermal inkjet at (a) 1 pass (deposition; (b) 10 passes (depositions).

Fig. 2. Silver nanoparticles films to be used as SERS substrates were prepared using thermal inkjet technology. Dependence of SERS intensity with number of depositions correlated well with morphological evolution of the films.

brings numerous advantages such as: flexibility, high specific surface area for an efficient uptake and transport of analyte to boundaries of metal nano-structures, extremely low cost and simplicity of fabrication. The fabrica-tion, characterization, and SERS activ-ity of our substrate using 2,4,6-trini-trotoluene, 2,4-dinitrotoluene and 1,3,5-trinitrobenzene as analytes was also explored. The paper-based SERS substrates presented a high sensitiv-ity and excellent reproducibility for analytes employed, demonstrating a direct application in forensic science and homeland security. Estimated low limits of detection (LOD) under the area illuminated by the laser were 94 pg of TNT, 7.8 pg of 2,4-DNT and 0.88 pg of TNB. This clearly suggests that our flexible SERS-active substrate based on an Au-coated paper filter can be used to detect nitroaromatic HEM down to a sub-nanogram regime [11].

4. ProgressinVibrationalStandoffDetectionofHEM/HME

a. FourierTransformInfraredSpectroscopy

Infrared emission spectroscopy of traces of explosives deposited on substrates has been steadily developing. Problems related to weak (low power) excitation sources have been overcome by several approaches. First, the commercial source included with the Open Path (OP) FT-IR spectrometer (Bruker Optics EM-27) has been substituted by a carborundum source (used in commercial electrical clothes dryers). A 3-unit system coupled to a focusing reflector is currently under development. Emissivity measurements are now ratioed against a blackbody source (Fluke IR Calibrator, Model # 4180-156) rendering the possibility of reporting absolute emissivities. Second, both mid-IR telescopes: transmitter and receiver were factory designed to op-erate in traditional OP mode: divergently focusing to infinity. The source was continuously diverging and

at 12 m of range and beyond, energy density from the source was lost because of target dimensions (30.5 cm x 30.5 cm). Both telescopes were substituted by two sets of 3 lenses (as illustrated in Fig. 5 for the receiv-ing optics).A second alternative is being ex-plored. A novel, laser mediated method of remote thermal excitation followed by standoff IR detection is being assembled. Telescope based

Fig. 4. Proof-of-concept experiment in which Whatman® filter paper #1 was TIJ coated with Au-NP was used to collect TNT and TNB residues on luggage (down to 98 pg TNT and 0.88 pg TNB) with subsequent SERS analysis using a low cost, fiber coupled portable Raman spectrometer.

Fig. 5. Schematic diagram of 3-lens optical system to substitute reflective telescopes included in the commercial OP FT-IR system. Transmitter consists of 2 in. diam. ZnSe lenses and receiver of 4 in. diam. optics.

FTIR spectral measurements and hyperspectral FTIR systems will be used to examine surfaces containing trace amounts of target threat compounds used in explosives devices. Among the target threat chemicals are nitroaromatic/nitroaliphatic explosives (TNT, RDX, PETN), mixtures (Pentolyte), formulations (C4/Semtex) and homemade explosives. Objectives: To determine the feasibility of laser induced thermal emission (LITE) from thermally excited explosives residues on surfaces. To achieve this objective we must devise and apply detection algorithms to discriminate and identify threats. Extend the investigations from a short range (0.30 m) to mid-range standoff capability (10 m) with appropriate emission collection optics. A sensitivity require-ment of < 250 µg/cm2 has already been attained and significantly lower detection limits for a fielded system are expected. Real-time imaging data of the explosives distribution over a surface can also be achieved. Fig. 6 illustrates the setup.The necessity of collimated and coherent light sources in the MIR is evidenced by the range limitation of the experiments described above. Even when coupled to IR telescopes to direct the light source on the substrates containing the target HEM, the energy/area of the system described in the OP FT-IR measurements would greatly benefit from a monochromatic, coherent, collimated and polarized source: a laser. The development of lasers with the ability to emit radiation in the 3-12 μm (833–3330 cm-1) spectroscopic range has advanced dramatically with the development of the quantum cascade lasers.Since the first demonstration of continuous-wave operation of MIR QCLs in 2002, the power levels of these la-ser systems have increased significantly. Coupling of QCLs to reflective IR telescopes that would enable their use as long range excitation sources is under evaluation in several research labs and private companies. Our work in development of methodologies based on QCL technologies follows a 3-pronged approach:• Evaluation of a commercial QCL based close range (6 in.) scanning trace detection system manufactured by Block Engineering (BE, Marlborough, MA). (See Fig. 7).• Involvement in development and testing a QCL source for IR microscopy applications, such as character-ization of HEM/HME. This is a transition effort involving an FT-IR microscopes company: Bruker Optics (Bil-lerica, MA), a QCL supplier: Eos Photonics (Cambridge, MA) and partners from academia (ALERT-UPRM).

Fig. 7. (a) BE QCL Scanner™ use in remote detection mode. (b) RDX QCL spectrum compared to reference spectrum. (c) Results of multivariate analysis (partial least squares, PLS) coupled to discriminant analysis.

Fig. 6. (a) Experimental setup for LITE. (b) Preliminary results for RDX detected at 8 m from source and comparison with reference spectrum obtained with MIR microscopy.

• Design, development and use of a remote QCL based remote detection system (funded by DOD). The system is partly built from COTS (commercial off-the-shelf) components: scanning, high power 4-diode, 7-10 μm QCL source from Pranalytica (Santa Monica, CA), MCT detector from IR Associates (Stuart, FL), data acquisi-tion and analysis hardware and software from National Instruments (Austin, TX). ZnSe optical QCL trans-mitter and reflected signal collector were designed in house and fabricated to our specifications by Spectral Systems (Hopewell Junction, NY) (See Fig. 8.)

b. RamanSpectroscopy

Work in Raman spectroscopy during YR-4 centered on two important aspects:• Remote Raman Spectroscopy was used to detect mixtures of HEM with non-HEM at 8m from thedetection system. The experiments were planned with chemometrics concepts so as to obtain the statistically relevant data. Among the most significant results were: detection of components in mixtures with high signal/noise; training of sensor “on the fly”: calibration curves were obtained from spectral information of mixtures; high

discrimination capability: HEM vs. Non-HEM.• Remote Raman Spectroscopy was used to detect mixtures of HEM with non-HEM at 8m from the detec-tion system. The experiments were planned with chemometrics concepts so as to obtain the statistically rel-evant data. Among the most signifi-cant results were: detection of com-ponents in mixtures with high signal/noise; training of sensor “on the fly”: calibration curves were obtained from spectral information of mixtures; high discrimination capability: HEM vs. Non-HEM.• Remote Raman Spectroscopy was used to determine low limits of detec-tion (LOD) values at 10 m from detec-tion system (see Figure 9 and Table 1.)

Fig. 8. (a) Remote Raman system. (b) Spectra of 4 components and one of the 28 mixes analyzed. (c) Calibration run for TNT obtained from mixtures. (d) PLS-DA analysis of mixes: explosive present represented by “1”; no explosive present: “0”.

Fig. 9 (top): (a) Variable diameter cell for remote Raman measurements. (b) Laser area vs. sample area. (c) Laser specifications.Table 1 (bottom): Results for limits of detection.

Name Institution Sponsor1 Gómez Rivera, Francisco UPR-PONCE ALERT2 Gonzalez, Lucas CORNELL ALERT3 Torres, Christian UPR-RIO PIEDRAS DOD-HBCU/MI4 Morrill, Samantha NORTHEASTERN UNIV. ALERT5 Figueroa Navedo, Amanda UPR-MAYAGUEZ DOD-HBCU/MI6 López Maisonet, Miguel A. UPR-MAYAGUEZ DOD-HBCU/MI7 Hidalgo Santiago, Migdalia UPR-MAYAGUEZ DOD-HBCU/MI8 Pollock Morales, Yadira INTERAMERICAN U. DOD-HBCU/MI9 Garcia Rosario, Allison Dr. CARLOS GONZALEZ

HS AGUADA, PRSAN GERMAN, PR

10 Gonzalez Sosa, Roxannie UPR-MAYAGUEZ DOD-HBCU/MI11 Millán Barea, Luis Rubén UPR-MAYAGUEZ DOD-HBCU/MI12 Moorer, Kiara TUSKEGEE U., AL DHS Summer Research Team

Program for Minority Serving Institutions

13 Aparicio-Bolaños, Joaquin, Dr. UPR-PONCE ALERT14 Mbah, Jonathan, Dr. TUSKEGEE U., AL DHS Summer Research Team

Program for Minority Serving Institutions

A. EducationalActivitiesandCommitment

There is a strong commitment in the F2-F ALERT component to education and training at all levels: from high school to post-doctoral trainees. Table 2 illustrates the main factors used to measure the productivity and effectiveness. During the summer of 2012 the Research Experiences for Undergraduates was extended to host 13 under-graduate students and two visiting professors.

Table 2. Productivity factors in F2-F ALERT component at UPR-M: first 4 years of project operation.

Table 3. F2-F Year 4 REU Participants.

IV. FUTURE PLANS

Our plan to further achieve state of the art advances in remote Raman detection of threat chemicals includes the following:• PerformRaman/IR experiments: PLS-DA, limits of detection (LOD)/quantification (QUANT)• Transition point detection QCL-Remote IR systems to industrial partners• Design, assemble, test and evaluate filter based hyperspectral Raman and QCL systems• Establish a testbed facility for testing detection technologies and algorithms.• Work on coupling QCL source to IR microscope for HEM/HME characterization studies• Demonstrate laser induced IR Emission Spectroscopy for detection of HEM/HME on substrates• Use a QCL Based IR Reflection Spectroscopy System for detection of HEM/HME• SERS detection of TNT and Bacillus thuringiensis (Bt) as model for bio-threats detection

V. RELEVANCE AND TRANSITION

Several transition projects were started during Years 3-4 and will be continued during Year 5:PROJECT I: AGILTRON-ALERT F2-F: Mobile Device Operated Handheld Raman SpectrometerExplosives detection and identification is one of the central tasks of homeland security personnel, particu-larly with the recent proliferation of improvised explosive devices (IEDs) worldwide. Instruments that can be used in the field to rapidly and accurately identify various explosives and their precursors are integral tools for first responders. Agiltron and ALERT-DHS Center of Excellence for Explosives will jointly develop a hand-held Raman spectrometer that can be operated by one or several commercial smartphones™ and a Raman spectral database for in-field identification of explosives. This will be a breakthrough in the area of handheld solutions for First Responders: • Development of Raman system with capabilities to detect and identify HEM and to transmit in a bidirec-

tional way data from the field to a central database using a Smartphone.• Main objective: to develop a spectral database for in-field detection of HEM.• Evaluate detection of HEM, HME, formulations and mixes Agiltron will be responsible for hardware design and application software development. The University of Puerto Rico at Mayagüez, an ALERT partner institution, will be responsible for creating the Raman spectral database using the Agiltron instrument as well as expert guidance to a Graphical User Interface (GUI) perti-nent to explosives identification by first responders.PROJECT II: BLOCK ENGINEERING: QCL Scanner HE Proximity Detector The Block Engineering LaserScan™ Analyzer is a powerful tool in detecting and analyzing trace explosives at close range (6 in.). However, algorithms will expand the applications for the device which will enhance its usefulness and ultimate potential for DHS with evident applications for detecting chemical threats by First Responders. ALERT’s expertise in algorithms for hyperspectral imaging will be leveraged to develop algo-rithms for the LaserScan. The University of Puerto Rico ALERT research team will work in testing the spec-troscopic system for sensing of highly energetic materials (HEM, including high explosives) and homemade explosives (HME) in real world environments. The team will focus on the design of algorithms to both iden-tify the HEM/HME threat and discriminate it against interferents. Development of algorithms will enhance detection, particularly addressing two main of explosives research: • Interferents: effects of substrates, mixtures and atmospheric interferences

• Differentiating Explosives from Background: Differential spectroscopy can discriminate between a sub-stance of interest and background by looking at a large area to train the algorithm on what the back-ground is and the differences when it encounters contamination.

PROJECT III: EOS PHOTONICS QCL excitation sources for RIRS• Current limitations in RIRS detection of HEM/HME: range and low limits of detection (LOD) resides pri-

marily on the excitation source when using Open Path FTIR.• Development of applications of high power QCL with broad excitation envelope (6-12 mm).Adaptation to reflective MIR telescopes is proposed. Figures shown depict the proof of concept of the idea in which a modest power QCL and an OP-FTIR (without the collection telescope) were capable of measuring TNT spectra of samples < 1 mg on a reflective metal substrate.

VI. LEVERAGING OF RESOURCES

An SBIR proposal from EOS Photonics (Cambridge, MA), Thermos Scientific (formerly Ahura, Tewksbury, MA) and ALERT-F2-F (UPRM) has been approved by DTRA. The joint effort entitled “IED Sentry Based on Mid-Infrared Laser Arrays” will use Monolithic Distributed Feedback (DFB) Quantum Cascade Laser Arrays (QCLA) coupled to reflective MIR telescopes/expanders and advanced chemometrics for compact and rugged standoff detection of explosives with no moving parts. Aimed at “First Responders” and military personnel engaged in theater operations, the system will comply with the requirement of “non-expert user need.” The operator will simply point and shoot the Sentry-QCL™ at the target and push a single button. An integrated processor will evaluate the return signal using a chemometrics database and display a clear identification of the threat, if such a threat exists, and the confidence interval with which it has been identified. Phase I research will include the design of a broadly tunable QCL source covering the spectral range from 7 to 10 m and the development of a detection system for short distance standoff detection of explosives. These designs will guide the fabrication of Phase I breadboard components. That will allow to study and evaluate the performance of our standoff checkpoint detection system. Based on these results the team will optimize the design for the improved prototype that will be realized in Phase II. Testing will be done at the proposed ALERT-F2-F Test-Bed facility to be established at Chemistry-UPRM during YR 5 of the COE operation.

VII. DOCUMENTATION

A. Publications

1. Castro-Suarez, J.R., Pacheco-Londoño, L.C., Vélez-Reyes, M. Diem, M., Tague, Jr., T.J. and Hernandez-Rivera, S.P., Open-Path FTIR Standoff Detection of TNT on Aluminum Surfaces, Applied Spectroscopy, 2012, SUB-MITTED.

2. Fierro Mercado, P.M. and Hernández-Rivera, S.P., Highly Sensitive Filter Paper Substrate for SERS Trace Explosives Detection, Int. J. Spec., 2012; SUBMITTED.

3. Fierro Mercado, P.M., Rentería-Beleño, B. and Hernández-Rivera, S.P. Fabrication of SERS-Active Sub-strates Using Thermal Inkjet Technology, Chem. Phys. Lett., 2012, SUBMITTED.

4. Hernández-Rivera, S.P. and Infante-Castillo, R., Predicting the heat of explosion of nitroaromatic com-pounds through their NBO charges and the 15N NMR chemical shifts of the nitro groups, 2012, Adv. Phys. Chem., ACCEPTED.

5. Espinosa-Fuentes, E.A. Pacheco-Londoño, L.C. Barreto-Cabán. M.A. and Hernández-Rivera, S.P. Novel Un-catalyzed Synthesis and Characterization of Diacetone Diperoxide, 2012, Propellants Explos. Pyrotech. ACCEPTED

6. Félix-Rivera, H., González, R., Rodríguez, G.D. Primera-Pedrozo, O.M., Ríos-Velázquez, C. and Hernández-Rivera, S.P., Improving SERS Detection of Bacillus thuringiensis using Silver Nanoparticles Reduced with Hydroxylamine and with Citrate Capped Borohydride, 2011, Int. J. Spectrosc., ACCEPTED.

7. Ortiz-Rivera, W., Pacheco-Londoño, L. C., Castro-Suarez, J. R., Felix-Rivera, H., Hernandez-Rivera, S. P., Vi-brational spectroscopy standoff detection of threat chemicals, 2011, Proc. SPIE Int. Soc. Opt. Eng., 8031, 803129.

8. Herrera, G. M., Félix, H., Fierro, P. M., Balaguera, M., Pacheco, L., Briano, J. G., Marquez, F., Ríos, C., Hernán-dez-Rivera, S. P., Nanosensors: from near field to far field applications, 2011, Proc. SPIE Int. Soc. Opt. Eng., 8031, 80312X.

9. Castro-Suarez, J. R., Pacheco-Londoño, L. C., Ortiz-Rivera, W., Vélez-Reyes, M., Diem, M., Hernandez-Rivera, S. P., “Open path FTIR detection of threat chemicals in air and on surfaces, 2011, Proc. SPIE Int. Soc. Opt. Eng., 8012, 801209.

10. Castro-Suarez, J.R., Pacheco-Londoño, L.C., Vélez-Reyes, M. Diem, M., Tague, Jr., T.J. and Hernandez-Rivera, S.P., Open-Path FTIR Detection of Explosives on Metallic Surfaces in “Fourier Transforms: New Analytical Approaches and FTIR Strategies”, 2011, G. S. Nikolić, ed. InTech Open, Croatia, 978-953-307-232-6.

11. Primera-Pedrozo, O.M., Pacheco-Londoño, L.C. and Hernandez-Rivera, S.P., Applications of Fiber Optic Coupled-Grazing Angle Probe FT Reflection-Absorption IR Spectroscopy in “Fourier Transforms: New Analytical Approaches and FTIR Strategies”, 2011, G. S. Nikolić, ed. InTech Open, Croatia, 978-953-307-232-6.

12. Pacheco-Londoño, L.C., Aparicio-Bolaño, J. Primera-Pedrozo, O.M. and Hernandez-Rivera, S.P., Growth of Ag, Au, Cu, and Pt Nanostructures on Surfaces by Micropatterned Laser Image Formations, 2011, Applied Optics, 50 (21), 4161–4169.

13. Palomera, N. Balaguera, M. Arya, S. K. Hernández, S., Tomar, M. S., Ramírez-Vick, J. E. and Singh, S. P., Zinc Oxide Nanorods Modified Indium Tin Oxide Surface for Amperometric Urea Biosensor, 2011, J. Nanosci. Nanotechnol. 11: 1–7.

B. TechnologyTransfer

Two provisional patents applications (PPA) have been granted during the period that covers this report:1. PPA for invention of Surface Enhanced Raman Spectroscopy Gold Nanorods substrates for detection of

TNT and 3,5-dinitro-4-methylbenzoic acid explosives. PPA # 61/471,520, Apr. 4, 2011.2. PPA for invention of Synthesis of Ag, Cu, Pt, and Au Nanostructures for Continuous Deposits on Surfaces

by Micro-Patterned Laser Image Formation. PPA # 61/471,478, Apr. 4, 2011.

C. Seminars,WorkshopsandShortCourses

Invited seminar at Metropolitan University, Ana G. Mendez Foundation, San Juan, Puerto Rico.

VIII. REFERENCES

[1] Steinfeld, J.I. and Wormhoudt, J., Annu. Rev. Phys. Chem. 49, 203 (1998).[2] Moore, D.S., Rev. Sci. Instrum. 75, 2499 (2004).[3] Moore, D.S., Sensing and Imaging: An International Journal 8(1), 9 (2007).[4] Primera-Pedrozo, O.M., Soto-Feliciano, Y.M., Pacheco-Londoño, L.C. and Hernández-Rivera, S.P., “High Explosives Mixtures Detection Using Fiber Optics Coupled: Grazing Angle Probe/Fourier Transform Reflec-tion Absorption Infrared Spectroscopy”, 2008, Sens Imaging, 9(3-4): 27-40.

[5] Primera-Pedrozo, O.M., Soto-Feliciano, Y.M., Pacheco-Londoño, L.C. and Hernández-Rivera, S.P., “Detec-tion of High Explosives Using Reflection Absorption Infrared Spectroscopy with Fiber Coupled Grazing Angle Probe / FTIR”, 2009, Sens. Imaging, 10 (1): 1-13.[6] Pacheco-Londoño, L.C., Primera-Pedrozo, O.M., Hernández-Rivera, S.P., Evaluation of Samples and Stan-dards of Energetic Materials on Surfaces by Grazing Angle-FTIR Spectroscopy in “Fourier Transform Infrared Spectroscopy: Developments, Techniques and Applications”, Rees, O.J., ed., Chemical Engineering Methods and Technology Series, Nova Science Publishers, Inc. Hauppauge, NY, 2010, ISBN: 978-1-61668-835-6.[7] Primera-Pedrozo, O.M., Soto-Feliciano, Y.M., Pacheco-Londoño, L.C., Hernández-Rivera, S.P., Fiber Optic-Coupled Grazing Angle Probe-Fourier Transform Reflection Absorption Infrared Spectroscopy for Analysis of Energetic Materials on Surfaces, in “Fourier Transform Infrared Spectroscopy: Developments, Techniques and Applications”, Rees, O.J., ed., Chemical Engineering Methods and Technology Series, Nova Science Pub-lishers, Inc. Hauppauge, NY, 2010, ISBN: 978-1-61668-835-6.[8] Primera-Pedrozo, O.M., Pacheco-Londoño, L.C. and Hernandez-Rivera, S.P., Applications of Fiber Optic Coupled-Grazing Angle Probe FT Reflection-Absorption IR Spectroscopy, in “Fourier Transforms: New Ana-lytical Approaches and FTIR Strategies”, 2011, G. S. Nikolić, ed. InTech Open, Croatia. ISBN: 978-953-307-232-6.[9] Gaensbauer, N., Wrable-Rose, M. Nieves-Colón, G., Hidalgo-Santiago, M., Ramírez, M. Ortiz, W., Primera-Pedrozo, O.M., Pacheco-Londoño, Y.C., Pacheco-Londoño, L.C. and Hernandez-Rivera, S.P., Applications of Op-tical Fibers to Spectroscopy: Detection of High Explosives and other Threat Chemicals, in Optical Fibers / Book 4, Moh, Y., Harun, S.H. and Arof, H., eds., 2012, InTech Open, Croatia, ISBN 979-953-307-653-8.[10] Wrable, M., Primera-Pedrozo, O.M., Pacheco-Londoño, L.C. and Hernandez-Rivera, S.P. “Preparation of TNT, RDX and Ammonium Nitrate Standards on Gold-on-Silicon Surfaces by Thermal Inkjet Technology”, 2010, Sens. Imaging. 11: 147-169.[11] Espinosa-Fuentes, E.A., Peña-Quevedo, A.J., Pacheco-Londoño, L.C., Infante-Castillo, R. and Hernández-Rivera, S.P., A Review of Peroxide Based Homemade Explosives: Characterization and Detection, in “Explosive Materials: Classification, Composition and Properties”, Janssen, T.J., ed., Chemical Engineering Methods and Technology Series, Nova Science Publishers, Inc. Hauppauge, NY, 2010, ISBN: 978-1-61761-188-9.[12] Espinosa-Fuentes, E.A. Pacheco-Londoño, L.C. Barreto-Cabán. M.A. and Hernández-Rivera, S.P. Novel Uncatalyzed Synthesis and Characterization of Diacetone Diperoxide, 2012, Propellants Explos. Pyrotech. Accepted for publication, 2012.[13] Fierro Mercado, P.M., Rentería-Beleño, B. and Hernández-Rivera, S.P. Fabrication of SERS-Active Sub-strates Using Thermal Inkjet Technology, Chem. Phys. Lett., 2012, SUBMITTED.[14] Fierro Mercado, P.M. and Hernández-Rivera, S.P., Highly Sensitive Filter Paper Substrate for SERS Trace Explosives Detection, Int. J. Spec., 2012; SUBMITTED.[15] C.W. van Neste, L. R. Senesac, and T. Thundat, “Standoff spectroscopy of surface adsorbed chemicals,” Anal. Chem. 81(5), 1952–1956 (2009).[16] Hildebrand, J. Herbst, J. Wollenstein, J., Lambrecht, A., Razeghi, M., Sudharsanan, R. and Brown, G.J. “Ex-plosive detection using infrared laser spectroscopy,” Proc. SPIE 7222(1), 72220B (2009).[17] Hinkov, B., Fuchs, F., Kaster, J.M., Yang, Q., Bronner, W., Aidam, R., Kohler, K., Carrano, J.C. and Collins, C.J. “Broad band tunable quantum cascade lasers for stand-off detection of explosives,” Proc. SPIE 7484(1), 748406, 2009.[18] Curl, R.F., Capasso, F., Gmachl, C., Kosterev, A. A., McManus, B., Lewicki, R., Pusharsky, M., Wysocki, G., and Tittel, F.K., “Quantum cascade lasers in chemical physics,” Chem. Phys. Lett. 487(1–3), 1–18 (2010).