LIFETIME MEASUREMENTS FOR $d^{1}\Sigma - c^{1}\Pi$ TRANSITION OF NH AND ND

Abstract

We have used an electron-beam source which is modulated at different radio frequencies for exciting the spectra of $ammonia^{1}(NH_{3})$ and $ND_{3}$ gases. A 0.5-meter seya-Namioka monochromator is used with an EMI 6256-B photo-Multiplier to record the spectra around 2530 {\AA}. The phase-shift between the input excitation and the emitted radiation is related to the lifetimes of the excited state $d^{1}\Sigma$ of NH and ND. The cascading lifetime parameters are calculated. The individual rotational lifetime for the P, Q, and R branches is measured. The possibility of the predissociation of this state will be $discussed.^{2}$.