Electric field measurements by Doppler-free Stark spectroscopy of the low-excited levels of atomic hydrogen

Abstract

A laser spectroscopic method for electric field measurements that observes the Stark spectra of the low excited levels n = 2 and n = 3 of atomic hydrogen has been explored. As advantage these levels can be excited Doppler‐free from the ground state by a single tuneable pulsed UV laser and the highly resolved Stark spectra are easy to understand and to be calculated. Using hydrogen and deuterium the Stark spectra of the n = 2 level are detected as optogalvanic signal. For three different cases of laser polarization the n = 3 spectra of hydrogen are measured simultaneously with optogalvanic and laser induced Balmer alpha fluorescence detection. Electric fields down to 200 V/cm can be determined from the Stark spectra of n = 2 level, while the spectra of n = 3 level enable measurements of electric fields as small as 50 V/cm in each of the three cases of laser polarization.