Vibrational spectra of N2: An advanced undergraduate laboratory in atomic and molecular spectroscopy

We describe an advanced undergraduate experiment to demonstrate molecular spectroscopy by measuring the vibrational energy spacing of nitrogen molecules in the gas phase. We show how the use of a simple and readily available AC discharge tube and a handheld spectrometer allows students to observe and measure the radiative collisional phenomena in the gas, and to scrutinize the resulting emission spectrum for an instructive analysis of the quantized vibrational potential of neutral as well as ionized N2.