Radical Intermediates in the Addition of OH to Propene: Photolytic Precursors and Angular Momentum Effects

ISMS 2014Matthew Brynteson, Carrie Womack, Ryan Booth,

Shih-Huang Lee, Jim Lin, and Laurie Butler

OH + Propene

+

OH propene

193 nm

193 nm

2-bromo-1-propanol

1-bromo-2-propanol

CCSD(T)/cc-PVDZ//B3LYP/cc-pVDZHuynh et al. J. Phys. Chem. A, 2009, 113, 3177-3185.

CCDCamera

MCP Detector & Phosphor

ScreenElectrostatic Lenses

Photolysis Laser (193 nm)

Pulsed Valve

skimmer

+2000 V +1424 V ground

REMPI for Br and Br*

10.5 eV Photoionization

750V

He

Velocity Map Imaging Apparatus

70% 1-bromo-2-propanol30% 2-bromo-1-propanol

𝐸𝑣𝑖𝑏=𝐸h𝑣+𝐸𝑝𝑟𝑒𝑐𝑢𝑟𝑠𝑜𝑟 −𝐸𝑇 −𝐷0 (𝐶−𝐵𝑟 )−𝐸𝑟𝑜𝑡−𝐸𝐵𝑟 ( 𝑃❑2

𝐽 )

0

0.02

0.04

0.06

0.08

0.1

0 10 20 30 40 50 60

P(E

T)

Energy, kcal/mol

-0.0002

0

0.0002

0.0004

0.0006

0.0008

0 1000 2000 3000 4000

P(v

)

Speed (m/s)0

10

20

30

40

50

60

70

80

0 20 40 60 80 100Time-of-Flight (sec)

m/z = 31 (CH2OH+)

Sig

na

l C

ou

nts

�⃑�❑=𝒓 × �⃑�𝒓�⃑� 𝐸𝑟𝑜𝑡=

12�⃑� 𝑇❑ 𝑰

−𝟏 �⃑�❑

C3H6OH Ethene + CH2OH+ionization

C3H6OH+dissociation

Dissociation!

0 0.2 0.4 0.6 0.8 1

P(E

T"/

ET')

ET"/E

T'

ET’ ET”

30 kcal/mol

Radical + Br

30 kcal/mol

30 kcal/mol

9 – 18 kcal/mol

OH + Propene

3 – 12 kcal/mol0 – 4.5 kcal/mol

𝑰−𝟏 �⃑�=�⃑�

𝑣=�⃑�  × r⃑  

Erot = 19 kcal/mol

0

0.1

0.2

0.3

0.4

0.5

0 5 10 15 20 25 30

P(E

T")

ET" (kcal/mol)

0

1 10-6

2 10-6

3 10-6

4 10-6

5 10-6

0 1000 2000 3000 4000 5000

P(v

)

v, speed (m/s)

0

2 10-6

4 10-6

6 10-6

8 10-6

1 10-5

0 500 1000 1500 2000 2500 3000

P(v

)

v, speed (m/s)

0

400

800

1200

1600

0 28 56 84 112 140

Sig

nal

Co

un

ts

m/z = 42 (C3H

6

+)

Time-of-Flight (sec)

0

100

200

300

400

500

600

7000 50 100 150 200 250

Time-of-Flight (sec)S

ign

al C

ou

nts

m/z = 17 (OH+)

OH Net Speed

Propene Net Speed

radicalOH

Net velocity

OH Net Speed

CD2CD2 Net Speed

radicalOH

Net velocity

-50

0

50

100

150

200

250

300

350

0 30 60 90 120

Sig

nal

Co

un

ts

Time-of-Flight (sec)

m/z = 32 (CD2CD

2

+)

0

100

200

300

400

500

600

7000 42.5 85 127.5 170

Sig

nal

Co

un

ts

Time-of-Flight (sec)

m/z = 17 (OH+)

0

1 10-6

2 10-6

3 10-6

4 10-6

5 10-6

0 1000 2000 3000 4000 5000

P(v

)

v, speed (m/s)

0

1 10-6

2 10-6

3 10-6

4 10-6

5 10-6

6 10-6

7 10-6

0 500 1000 1500 2000 2500 3000 3500

P(v

)

v, speed (m/s)

193 nm+

Thank You!• Butler Group– Dr. Carrie Womack*– Dr. Ryan Booth*– Dr. Chow-Shing Lam*– Lei Wang– Jon Adams– Preston Scrape– Prof. Laurie Butler*