Evidence of quantum ergodicity in stimulated emission pumping spectra of acetylene

We investigate the stimulated emission pumping (SEP) spectra of the acetylene X̃ 1∑+g state near 27 900 cm−1 of vibrational excitation for evidence of quantum ergodicity. The spectra consists of clumps of narrowly spaced lines which arise from transitions into levels with the same lower state J″ value. Thus, the structure within each clump is purely vibrational. We apply criteria for spectral ergodicity and examine nearest-neighbor spacing distributions to test the spectra for signs of ergodic molecular dynamics. The criteria applied suggest that the molecular dynamics is nearly ergodic.