For the Lab covering the weeks of 10/13/2008 and 10/20/2008, I have chosen to do the Balmer series, where after calibration of an optical spectrometer, I will measure the spectral lines of hydrogen and deuterium.
For the Lab, I am using a model SP200 5000 Volt, 10mA Spectrum Tube Power Supply, produced by Electro-Technic Products, using spectral tubes of mercury, hydrogen, and deuterium.
For measuring the data I am using a "constant-deviation" spectrometer, with a Pellin-Broca constant-deviation prism acting to determine the different wavelengths.
The full procedure can be accessed in Professor Gold's Lab manual here
Measured values vs. known values of Mercury spectral wavelengths
Known Values
Measured Values
404.7nm
404.2nm
435.8nm
435.9nm
546.1nm
546.0nm
577.0nm
576.9nm
579.0nm
579.0nm
690.75nm
700.0nm
When calibrating the spectrometer, I had a wide variance in measurements, and had extreme differences in measurements depending on the wavelength. I settled on zeroing the spectrometer such that it had the closest values for the 546.1 and 577 nanometer readings and ignore that the red line had a significantly higher reading than what would be expected.
Measured values of Hydrogen spectral wavelengths
Line
1
2
3
1
409.4nm
409.6nm
409.3nm
2
433.1nm
433.3nm
433.2nm
3
484.8nm
485.0nm
485.0nm
4
654.3nm
654.1nm
654.0nm
Measured values of Deuterium spectral wavelengths
Line
1
2
3
1
409.4nm
409.3nm
409.5nm
2
433.2nm
433.1nm
433.2nm
3
484.5nm
485.0nm
484.8nm
4
654.1nm
653.8nm
654.5nm
My method of measurements was to start at the highest wavelength possible and work my way down the spectrum, taking measurements as I go. After finishing a set of measurements for Hydrogen, I switched to the deuterium and took my measurements. I repeated the set 3 times, without touching the crystal and possibly changing the calibration in between sets.
After completing these measurements, I decided to take another set of data with a different calibration so that I would have another calibration slope, hopefully giving more accurate results.
For these data sets I am measuring from the lowest possible wavelength on the spectrometer up, with the calibration done first then hydrogen then deuterium.
Measured values vs. known values of Mercury spectral wavelengths
Known Values
Measured Values
404.7nm
404.5nm
435.8nm
435.8nm
546.1nm
545.9nm
577.0nm
577.1nm
579.0nm
579.5nm
690.75nm
699.1nm
Measured values of Hydrogen spectral wavelengths
Line
1
2
3
1
409.7nm
409.8nm
409.9nm
2
434.0nm
433.9nm
434.0nm
3
485.7nm
485.7nm
485.8nm
4
656.0nm
657.0nm
656.8nm
SJK 00:18, 3 November 2008 (EST)00:18, 3 November 2008 (EST) Looks like you did some deuterium measurements, but did not crunch the numbers, right? Well, it does look like they're indistinguishable in your measurements.
Measured values of Deuterium spectral wavelengths
Line
1
2
3
1
409.8nm
409.7nm
410.0nm
2
433.9nm
433.9nm
434.0nm
3
485.0nm
485.3nm
485.4nm
4
656.1nm
656.5nm
656.8nm
The last portion of the lab asks for us to measure the resolving power of the spectrometer using Sodium and the double yellow spectral lines at 589.0 and 589.6 nanometers. Unfortunately, we do not have a spectral tube containing sodium vapor, so I was unable to see if it was possible to measure the difference between the two lines.
Project name
Main project page
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