Lab 7: Spectroscopy
INTRODUCTION
In physics, the study of spectroscopy involves the process of obtaining a spectrum,
usually from the absorption and emission of light or electromagnetic radiation and graphing that
energy in the form of wavelengths and their intensity. This lab required us to become familiar
with the scientific software and materials (spectrometer) involved in obtaining a spectrum of
light. An essential element in this lab is the utilization of a dilute (low-pressure) gas that has an
applied voltage that excites the gas, causing light to be emitted. In essence, adding voltage to a
gas excites the electrons in the atom. When the excited electrons lose that energy and go back to
the resting state, light, in the form of a photon, will emanate. From the photon, we measure the
color of the light in the form of wavelengths and frequencies. The spectrometer records this
phenomenon occur by evaluating how much color is released from the photon. A spectrum is
then displayed in the form of a graph. Spectroscopy is essential in everyday life by identifying
different molecular compounds in certain fields. For example, spectroscopy can be used in
forensic science by distinguishing between the chemical materials in a piece of evidence by
examining the reflection of wavelengths. It can also be used in the food industry by identifying
different microbes/pests that can be hidden in our food by using UV-fluorescent techniques.
PROCEDURE
To begin, we set up the software needed to obtain the spectrum graph. We started up the
OceanView application. From this, we obtained a graph that measured the wavelength vs the
frequency. We also set up the spectrometer and cable to ensure that we measure the light emitted
from the tube. When this was done, we then placed the Helium Discharge tube in the tube holder
and turned on the power supply and saw that the tube began to glow. To get a good spectrum, we
adjusted the collector. Then, we observed the spectrum graph as the spectrometer picked up the
, wavelengths. When we got a good batch of data, we paused the data acquisition and turned off
the power to the tube. We repeated this procedure once more to examine the hydrogen line by
inserting a Hydrogen Gas Tube. Then using the equation: , we calculated the predicted value of
the wavelength for the 3 to 2 transition (when an electron falls from the 3rd energy level to the
2nd, causing a photon to emit a wavelength).
DATA/CALCULATIONS/QUESTIONS
Experiment 1: Measure the spectrum of Helium
Wavelength of Largest Peak: 65,000
Table 1.0: Wavelength vs Counts for Helium Emission Spectrum
Wavelength [nm] Counts
350 46.25
352 -35.26
354 35.26
356 88.75
358 -77.77
360 -36.7
362 342.37
364 35.88
366 10360.64
368 202.61
INTRODUCTION
In physics, the study of spectroscopy involves the process of obtaining a spectrum,
usually from the absorption and emission of light or electromagnetic radiation and graphing that
energy in the form of wavelengths and their intensity. This lab required us to become familiar
with the scientific software and materials (spectrometer) involved in obtaining a spectrum of
light. An essential element in this lab is the utilization of a dilute (low-pressure) gas that has an
applied voltage that excites the gas, causing light to be emitted. In essence, adding voltage to a
gas excites the electrons in the atom. When the excited electrons lose that energy and go back to
the resting state, light, in the form of a photon, will emanate. From the photon, we measure the
color of the light in the form of wavelengths and frequencies. The spectrometer records this
phenomenon occur by evaluating how much color is released from the photon. A spectrum is
then displayed in the form of a graph. Spectroscopy is essential in everyday life by identifying
different molecular compounds in certain fields. For example, spectroscopy can be used in
forensic science by distinguishing between the chemical materials in a piece of evidence by
examining the reflection of wavelengths. It can also be used in the food industry by identifying
different microbes/pests that can be hidden in our food by using UV-fluorescent techniques.
PROCEDURE
To begin, we set up the software needed to obtain the spectrum graph. We started up the
OceanView application. From this, we obtained a graph that measured the wavelength vs the
frequency. We also set up the spectrometer and cable to ensure that we measure the light emitted
from the tube. When this was done, we then placed the Helium Discharge tube in the tube holder
and turned on the power supply and saw that the tube began to glow. To get a good spectrum, we
adjusted the collector. Then, we observed the spectrum graph as the spectrometer picked up the
, wavelengths. When we got a good batch of data, we paused the data acquisition and turned off
the power to the tube. We repeated this procedure once more to examine the hydrogen line by
inserting a Hydrogen Gas Tube. Then using the equation: , we calculated the predicted value of
the wavelength for the 3 to 2 transition (when an electron falls from the 3rd energy level to the
2nd, causing a photon to emit a wavelength).
DATA/CALCULATIONS/QUESTIONS
Experiment 1: Measure the spectrum of Helium
Wavelength of Largest Peak: 65,000
Table 1.0: Wavelength vs Counts for Helium Emission Spectrum
Wavelength [nm] Counts
350 46.25
352 -35.26
354 35.26
356 88.75
358 -77.77
360 -36.7
362 342.37
364 35.88
366 10360.64
368 202.61
