Analyze emission spectra

Determine the wavelengths of light emitted from sources such as gas spectrum tubes.

Note

For a more detailed experiment procedure, see the Element identification from emission spectra sample experiment. Classroom-ready experiments are also available in the PASCO Experiment Library.

Procedure

This experiment requires the use of a Fiber Optic Cable. This cable is sold separately from the compatible spectrometers.

Insert the rectangular end of the Fiber Optic Cable into the cuvette holder.
Point the fiber optic window at the other end of the cable at a light source. Move the probe as close to the source as possible without touching the source.

Note

If the light source emits significant amounts of heat, place a transparent barrier between the light source and the probe to prevent damage to the window.
Start Chemvue, then connect your spectrometer to the program. The software should automatically open to the Spectrometry Module.
Switch to the light spectra page using the navigation bar.
Select Start to begin collecting data.

Tip

Select the Auto Set button under Integration Time if your data appears too noisy.
Once you have obtained sufficient data, select Stop to end data collection and keep the displayed data.
Select the Coordinates tool, then drag the coordinate data target to different points to measure the peak wavelengths.

Planck's Constant: Students use a voltage sensor and an AC/DC electronics laboratory to measure the turn-on voltage of various colors of LEDs and then plot the turn-on voltage versus LED frequency to determine the value of Planck's constant.