Analyzing Line Emission Spectra Viewed Through a Spectroscope Using a Smartphone

For almost a half century, general chemistry curricula have included a laboratory exercise that involves using spectroscopes to view line emission spectra. Due to the variable optics of these devices, students typically need to calibrate the scope with a mercury lamp prior to any actual measurements. This task entails plotting, by hand or using a spreadsheet, the wavelength of the emission line as recorded off of the scope’s reference scale versus literature values. Subsequent wavelength measurements are then adjusted based on this calibration curve. The calibrated scope is then used to measure the wavelengths of hydrogen emission lines; students calculate the Rydberg constant, etc. We recently developed a smartphone application utilizing the camera to calibrate the spectroscope, and once calibrated, the application can then be used to take additional measurements on other emission lines. The application can be easily incorporated into existing laboratory exercises.