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Atomic Spectrometer Laboratory Experiment Analysis
Vicky J. Mawuntu
NIM 10 310 868
Universitas Negeri Manado 2012
ATOMIC SPECTROMETER
A. GOALS OF EXPERIMENT
1. Calibrating spectrometer with Mercury and Neon spectrum by using graph method.
2. Determine the wavelength of the emission spectra of various atoms held various gases
in the tube lamps (Neon and Mercury) and determine the electron transitions.
B. EQUIPMENT AND MATERIALS
1. Spectrometer
2. Neon gas tubes and mercury.
3. Clamp Holder
4. Coil Rumkorf
5. Power suply
6. Prism
C. BASIC THEORY
Light is a transverse wave that includes electromagnetic waves. The properties
include light can experience reflection (reflection), refraction (refraction), stretching
(diffraction), absorbed the vibration direction (polarization), and described (dispersion).
The dispersion of white light into the events unraveling the colorful light. A white
light consists of several color spectrum wavelength divided by each. When a beam of light
passing through a transparent medium it will undergo refraction due to differences in
refractive index medium in its path. White light can be broken down into a colorful light
called polychromatic light while a single light that can not be described again called
monochromatic light.
Dispersion event also occurs when a beam of white light is passed at a prism to form a
spectrum of light. This spectrum can be observed through a spectrometer.
Prism is a transparent substance bounded by two plane. When a beam of light came
on one of the fields which is then referred to as a prism refracting the field I will be refracted
near normal line. Until the field of refractory II, the beam will be refracted away from the
normal line. In the field of refractory I, refracted rays approaching the normal, because the
light coming from the optical substance less dense to more dense optical substances, from air
to glass. In contrast to the field of refractory II, refracted rays menjahui normal line, because
the light coming from the optical substances meeting the optic substance that is less dense
than glass into the air. So that a beam of light passing through a prism will experience
deflection from the original direction.
The image above illustrates a beam of light passing through a prism. The figure shows
that the light beam in a prism having two kalipembiasan so that the light rays enter the prism
and the beam out of the prism is no longer parallel.
The angle formed between the direction of the beam comes to the direction of the
light leaving the prism is called the angle of deviation given the symbol D. The magnitude of
the deviation angle depends on the angle the light comes.
D = i1 + r2 - β
Where:
D = the angle of deviation
i1 = angle of incidence on the prism
r2 = left angle prism light refraction
β = angle peak or angle prism refracting
The amount of light depending on the angle of deviation angle of light coming into
the prism. If the point of arrival of the light is reduced, then the angle of deviation would be
even smaller. Will achieve the minimum deviation angle (Dm) if the angle of incidence of
light to the same prism light refraction angle prism or leave at that beam of light entering the
prism prism will cut it into an isosceles triangle, so it applies i1 = r2 = i (with i = angle), and i2
= r1 = r (with r = angle bias). Minimum deviation angle can be expressed as:
The incident light dispersion can be observed through a spectrophotometer. Beam of
light is used in the form of gas lamps fed high voltage, so that the lamp will emit light rays
with a wavelength-specific (depending on the type of gas used).
By putting the gas lamp (Hg) in front of the collimator, the beam towards one side of
the prism will form on the other side of the spectrum. This spectrum can be observed through
binoculars and note its position by reading the scale. if the spectrum is known wavelength,
the spectrometer can be calibrated, so that the spectrometer can be used to determine the
wavelength spectrum of an unknown substance.
Prism
Prism spectroscope is a device used to view the spectrum of a light source. Prism
spectrometer is an instrument used to measure the spectrum of light that break down after
passing through a medium or to measure the wavelength and the refractive index of a prism.
The composition comprises a prism spectrometer components collimator, telescope,
spectrometer table, and scale.
a. Collimator
Colimator is a tube fitted with a lens akromatik where one end (facing the prism) and
a gap. Collimator lens function is to align the beam coming out of the gap. Gap width can be
set using the regulator screw located on the end near the collimator slit. PC regulator screw is
used to adjust the width of the beam of light falling on the prism of the gap, while the
position of the lens can be set with couplers, PL. In use the prism spectrometer, the gap
associated with the light source to be observed spectra. The light source is enclosed in a tube
(so the light is not scattered) and slit parallel to the gap found on the collimator.
b. Telescope
The telescope is used terdri of objective and eyepiece lenses. The position of the
ocular lens of the objective lens can be adjusted with the screw, which is located on the end
of a telescope. The telescope can be moved-motion, in addition to functioning as a place to
see the spectrum of the light produced prism, telescope is able to show the resulting angle of
refraction prism. To determine the exact position of a gap, is used as a reference cross thread.
c. Table Spectrometer
Spectrometer table is a place for meletkkan prism. His position can be raised /
lowered or rotated by loosening the screws and mengeratkannya. Prism is an object that
distorts the spectrum of the light source.
d. Main Scale and Scale Nonius
Under the spectrometer table, there is a dish of the major scale and Nonius scale.
These scales indicate the resulting corner of refraction lens. In the major scale there are 360
large-scale shows the corner on a full circle. While the Nonius scale scales are smaller. The
number of scales on a scale swordfish Nonius fixed, it depends on the precision spectrometer,
the more Nonius scale and the smaller the distance from the scale of the one and the other,
the accuracy of the spectrometer is small anyway. And errors in the measurement are also
very small.
Working Principle Spectrometer
A spectrometer using a diffraction grating or a prism to separate the different
wavelengths of light. The working principle of the spectrometer is bring light through a
narrow gap called a collimator. This is the focus collimator lens, so that the light will be
transmitted in parallel. Light is parallel, then forwarded to the grid for later captured by
teleskope whose position can be moved. Wavelength measurements can be performed using a
diffraction grating spectrometers placed on the table. When light passes through a grating,
diffraction event occurs. In particular teleskope position is at an angle θ, is the position that
correspond to the pattern of light (maximum pattern).
For the prism spectrometer, parallel light then entered a prism. Here, light dispersion
or events experienced decomposition polikromarik light (white) to light-monochromatic light
because the refractive index difference.
A lens focuses light on out gap. Only one color of light that can pass through this gap
at a time. Therefore, the prism must be rotated to bring other colors into the exit slit and read
the entire spectrum. The scale of the circular noted that angle prism wavelength of light can
be determined.
But there is also a spectrometer that uses flat mirrors called gratting groove instead of
a prism. The surface of a gratting contains thousands of thin parallel grooves. The light that
penetrates gratting will produce a spectrum.
Spectrum Lines
Atomic electron stationary in particular has complete power expressed by numbers -
quantum numbers, namely:
n = 1,2,3, ......... (Called the principal quantum number)
l = 0,1,2, ...... (n-1) (referred to as the orbital quantum number)
ml = - l, (-l + 1), ..... l-1, l (called the orbital magnetic quantum numbers)
ms = ± s
Power of electrons in atoms form a kind of cedar - cedar effort, referred to as cedar
atomic energy, which for the atom - atom with a single electron. According to quantum
theory Bohr expressed as:
(
)
with:
R = 1, 097 x 107 m-1
is called the Rydberg constant
h = 6.625 x 10-34
Js called the Planck constant
c = 3 x 108 m/s as the speed of light.
Z as the atomic number
The electrons in an atom can move from cedar power (energy level) to another power
cedars following selection rules are:
Δl = ± 1 and Δml = 0, ± 1
Displacement of electrons in the atoms of a cedar energy onto a higher power can occur by
absorbing energy from the outside (either heat, kinetic energy, radiation workers, etc.). While
the transfer of electrons onto a lower generally accompanied by the emission of radiation
energy. Radiation of electromagnetic waves emitted by electrons moving from the cedar
force (which has principal quantum number n) to the level power with quantum numbers m
<n has a wave number that can be expressed by the equation:
(
)
where:
λ = wavelength of radiation
With the existence of electromagnetic waves emitted by the transition of electrons -
electrons in atoms emerged as the emission spectra / emission in atoms, which can be any
member information regarding quantitation and cedar - cedar energy of electrons in atoms.
The incident light dispersion can be observed through a spectrophotometer. Beam of light is
used in the form of gas lamps fed high voltage, so that the lamp will emit light rays with a
wavelength-specific (depending on the type of gas used).
In terms of the atomic emission spectrum lies in the visible region facilitate
observation and measurement wavelength. Wavelength as the wavelength spectrum of atoms
can be measured using Higler spectrometer, which was equipped with a wavelength scale.
Alternatively, you can use the new spectrometer equipped with an angular scale of the order
of minutes.
By using Mercury spectrum, where wavelengths are known from the literature:
No. Color λ(Ǻ)
1. Red 6907
2. Yellow 1 5789,7
4. Yellow 2 5769
5. Green 1 5460,6
6. Green 2 4916
7. Blue 4358,4
8. Violet 4358,4
9. Violet 4046,6
for the atom - atom Rydberg constant of the complex has been put on the principal quantum
number correlations in the Bohr formula so that the formula (3) becomes:
(
)
Where a and b is the deviation of the integers n and m, called the quantum defect.
D. STEPS OF EXPERIMENT
1. Set the spectrometer so that the eyepiece apparent cross gari with binoculars on a
collimator way also towards mercury lamp or lamps Helium (in a straight position)
2. Set the lens so that the object observed okulernya apparent.
3. Adjust so that the light from the source collimator looked sharp by adjusting the width
of the collimator slit as narrow as possible.
4. Putting prism spectrometer with a position on the table beside the clear prism-center
directional ketengah objective lens on the collimator.
5. Then pull aside the lenses of binoculars while observing the spectrum.
6. While observing through the lens prism binoculars rotary table so that the observed
spectrum prism moving in the direction of rotation and rotate again to turn the
spectrum reverse direction. Find the position of the turning point of the spectrum
rounds. (As the minimum angle of deviation angle spectrum).
7. By putting the crosshairs in the eyepiece at the position of each spectral line color
then measured how the angle formed by the line color of the spectrum.
8. Replace mercury lamp with Helium gas lights then follow steps 4-7 for each
measurement of the angle of deviation.
E. OBSERVATION DATA
Mercury Lamp
Straightening Angle : Left Nonius = 57
Right Nonius = 237
No Color
I II III I II III
1 Violet 1 16,5 4’ 16,5 4’ 16,5 4’ 196,5 4’ 196,5 4’ 196,5 4’
2 Violet 2 16,5 10’ 16,5 9’ 16,5 10’ 196,5 11’ 196,5 11’ 196,5 11’
3 Blue 16,5 27’ 16,5 27’ 16,5 28’ 196,5 27’ 196,5 27’ 196,5 27’
4 Green 1 17,5 17,5 17,5 197,5 197,5 197,5
5 Green 2 17,5 20’ 17,5 19’ 17,5 20’ 197,5 20’ 197,5 20’ 197,5 19’
6 Yellow 1 18 18 18 197,5 28’ 197,5 29’ 197,5 29’
7 Yellow 2 18 3’ 18 3’ 18 3’ 198 5’ 198 5’ 198 5’
Neon Lamp
Straightening Angle : Left Nonius = 57
Right Nonius = 237
No Color
I II III I II III
1 Violet 16,5 27’ 16,5 27’ 16,5 27’ 196,5 27’ 196,5 27’ 196,5 27’
2 Green 17,5 15’ 17,5 16’ 17,5 15’ 197,5 15’ 197,5 15’ 197,5 15’
3 Yellow 1 18 18 18 198 198 198
4 Yellow 2 18 1’ 18 2’ 18 1’ 198 2’ 198 1’ 198 2’
F. CALCULATION OF DATA
Mercury Lamp
Straightening Angle : Left Nonius = 57
Right Nonius = 237
No Color
I II III Average I II III Average
1 Violet 1 16,57 16,57 16,57 16,57 196,57 196,57 196,57 196,57
2 Violet 2 16,67 16,65 16,67 16,66333 196,68 196,68 196,68 196,68
3 Blue 16,95 16,95 16,97 16,95667 196,95 196,95 196,95 196,95
4 Green 1 17,5 17,5 17,5 17,5 197,5 197,5 197,5 197,5
5 Green 2 17,83 17,82 17,83 17,82667 197,83 197,83 197,82 197,8267
6 Yellow 1 18 18 18 18 197,97 197,98 197,98 197,9767
7 Yellow 2 18,05 18,05 18,05 18,05 198,08 198,08 198,08 198,08
Minimum Deviation Angle on prism of Mercury Lamp
o Violet I
o Violet II
o Blue
o Green I
o Green II
o Yellow I
o Yellow II
Neon Lamp
Straightening Angle : Left Nonius = 57
Right Nonius = 237
No Color
I II III Rata-
Rata
I II III Rata-
Rata
1 Violet 16,95 16,95 16,95 16,95 196,95 196,95 196,95 196,95
2 Green 17,75 17,77 17,75 17,75667 197,75 197,75 197,75 197,75
3 Yellow 1 18 18 18 18 198 198 198 198
4 Yellow 2 18,02 18,03 18,02 18,02333 198,03 198,02 198,03 198,0267
Minimum Deviation Angle on prism of Neon Lamp
o Violet
o Green
o Yellow 1
o Yellow 2
ANALYSIS
The emitted light vary in each gas and is characteristic of the gas. Light produced
helium gas and mercury gas in the lamp, having bending light waves passing through the
lattice, where the smaller lattice, the greater the spread of the wave. Then, the results of the
diffraction of light wave interference, so the binoculars visible color spectrum measured
angle shape.
Based on the calculations for each gas, violet spectrum has the shortest wavelength
and red the longest, ie
Gas Color Deviation Angle (o)
Mercury
Violet 1 40,43
Violet 2 40,33667
Blue 40,04333
Green 1 39,5
Green 2 39,17333
Yellow 1 39
Yellow 2 38,95
Neon Violet 40,05
Green 39,25
Yellow 1 39
Yellow 2 38,9733
Once the minimum deviation angle values obtained will then be sought wavelength of
the fluorescent light source with a wavelength spectrum of colors using a mercury lamp as a
reference. Of libraries used, obtained wavelength spectrum of colors on Mercury lamps are:
Yellow I = 5789,7
Yellow II = 5769
Green = 5460,6
Violet = 4046,6
In this experiment we used a prism to describe the color, with the aim of calculating
the wavelength of each spectrum.
The spectrum of light in the prism of the deflection of light caused by the prism. Prism
consists of two flat fields, diffusers I and II refractory. In the field of refractory I, refracted
rays approaching the normal, because the light coming from the optical substance less dense
to more dense optical substances, from air to glass. In contrast to the field of refractory II,
refracted rays menjahui normal line, because the light coming from the optical substances
meeting the optic substance that is less dense than glass into the air. So that a beam of light
passing through a prism will experience deflection from the original direction and formed a
spectrum of colors.
Dispersion of light is the decomposition of polychromatic light (white light) into a
monochromatic light (red, orange, yellow, green, blue, indigo, violet) by refraction or
bending. Different wavelengths of each color spectrum caused by differences in the angle of
deviation of the color spectrum.
Collimator serves to change the light / light into a parallel beam. Rays coming from
the source is diffuse rays (emanating all directions). By collimator diffuse light is converted
into a parallel beam before it is passed to the prism.
Determining Steps wavelength spectrum of colors by using charts
1. Determine the scale on the graph
2. Determining minimum deviation scale and wavelength (used graphs of minimum
deviation wavelength)
3. Plot points deviation angle which is the result of the experiments conducted
4. Mercury plotting wavelength of each color according to the reference spectrum of
wavelengths that exist in the library Mercury.
5. Determine the point of intersection obtained between the wavelength and the angle
of deviation of each spectrum. Then drag the lines connecting each cut point gained.
6. To determine the wavelength of Neon, note the location of the vertex deviation for
each spectrum and the location of the crossing point on the line spectrum of mercury.
Drag the vertical y-axis direction, until it touches the x-axis. Value read on the x-axis
that is a wavelength for the color spectrum.
40,43
40,33667
40,04333
39,5
39,17333
39 38,95
38,8
39
39,2
39,4
39,6
39,8
40
40,2
40,4
40,6
0 1000 2000 3000 4000 5000 6000 7000
Deviation Angle
Wavelength
MERCURY GAS
Wavelength in accordance with the observations by using graphical method is as follows:
No. Color λ(Ǻ)
1. Yellow 1 5980
2. Yellow 2 5768
3. Green 5332
4. Violet 4348
38,9733 39
39,25
40,05
38,8
39
39,2
39,4
39,6
39,8
40
40,2
0 1000 2000 3000 4000 5000 6000 7000
Deviation Angle
Wavelength
NEON GAS
Comparison of the wavelength spectrum of colors on the gas and the gas Mercury Neon:
No. Color
λ (Ǻ)
Mercury Neon
1. Violet 4046,6 -
2. Violet 4078 4348
3. Blue 4358,4 -
4. Green 1 4916 -
5. Green 2 5460,6 5332
6. Yellow 1 5769 5768
7. Yellow 2 5789,7 5980
Precentage of uncertainty of Color Spectrum on Mercury (Hg) Lamp
From the whole calculation of error precentage, we gain small error for the experiment.
The difference between the results of this lab with the existing theory, due to several possible
factors as follows.
1. The existence of a cracked prism, so that the light coming out of the prism
experienced assimilation, and difficult to see the color difference spectrum
2. Scale reading on the arc angle spectrometer is improper
CONCLUSION
In this experiment is defined wavelength spectrum of colors from neon to calibrate the
spectrometer using a graphical method, based on the wavelength spectrum of atomic
mercury
From the observations made, for Mercury gas spectrum obtained 7 colors, namely
purple I, II purple, blue, green I, II green, yellow I and II yellow. Largest minimum
angle of deviation found in the spectrum of the color purple I and smallest in the
yellow spectrum II. As for the wavelength, the spectrum has the largest wavelength
yellow II, while the smallest in the purple spectrum I.
From the observations made, for Neon gas spectrum obtained four colors, namely
purple, green, yellow I and II yellow. Minimum deviation angle on the spectrum are
the largest and smallest purple on yellow spectrum II. As for the wavelength, the
spectrum has the largest wavelength yellow II, while the smallest in the purple
spectrum.
Wavelength for each of the color spectrum on both the type of lamp, obtained
different results. However, the results did not differ significantly. When compared
with the reference of the wavelength, the deviation error for the determination of the
wavelength for each of the observed spectrum of colors can be quite small. This is
because the possibility of an error (error) in this experiment. Some things that cause
such error is parallax errors when determining crosshead for each line of the observed
spectrum, the less accuracy in the reading of the scale, as well as problems on the
device used.
SUGGESTION
Observers should consider prism is used, you should use a prism that has a good
condition, in order to get the results of the minimum deviation angle light throughput.
In this experiment required accuracy in measuring the angle of each order of the
spectrum. The difficulty of measuring and observing the room quite dark very
influential on the spectrometer scale reading accuracy.
Collimator gap should be set as narrow as possible (note that the observer can still see
the light at the slit collimator) to facilitate placement of crosshead on spectral lines.
Putting crosshead precisely the spectral lines is necessary in order to obtain a
thorough measurement angle.
LITERATURE
J,B. Moningka. 2012. Penuntun Praktikum Laboratorium Fisika I. Jurusan Fisika: FMIPA
UNIMA
http://anitanurdianingrum.blogspot.com/2011/08/laporan-spektrometer-sederhana.html