Sub-Doppler laser absorption spectroscopy of the A2Πi − X2Σ+ (1, 0) band of CN: Measurement of the 14N hyperfine parameters in A2Π CN

摘要: Abstract Measurements of multiple rotational lines in the (1, 0) band A 2 Π i  −  X Σ + “red” system cyanogen radical (CN) at sub-Doppler resolution are reported. The CN was produced by 193 nm photodissociation NCCN (ethane dinitrile) and detected with a Ti:sapphire ring laser operating near 10 900 cm −1 . sample exposed to weak, frequency-modulated probe beam strong, counterpropagating bleach beam. Demodulated signals display absorption dispersion features derived from Doppler-free saturation hyperfine components as scans across central region Doppler-broadened line spectrum. Hyperfine-resolved transition frequencies were combined known ground-state term values determine state values, which analyzed terms an effective Hamiltonian for state. All expected 14 N quadrupolar parameters determined their simple molecular orbital picture bonding radical. Higher sensitivity obtained 400 kHz amplitude modulation additional phase-sensitive detection allowed splittings some 13 C be observed natural abundance. Excited selection states, but not enough parameters.