Determination of lifetimes, optical excitation functions transmitted election spectra, optical spectra and quenching cross sections /

Abstract

An apparatus has been set up which allows the measurement of transmitted electron spectrum, radiative decay lifetimes and optical excitation functions of any gas molecules (atoms) in the region of visible and vacuum ultraviolet. For lifetime measurement a delayed coincidence photon counting technique has been used.

The optical excitation functions for these vibrational levels have also been measured. Multiple thresholds have been observed which appear to be due to overlapped vibrational levels of the d('3)(DELTA) and e('3)(SIGMA)('-) states. The thresholds obtained from emission functions agree with spectroscopically determined thresholds.

Optical spectra of CO were measured in the region of interest at many different electron energies to determine the extent of possible spectra overlap and to aid in the indentification of week band.

The optical emission function for Vacuum Ultra-Violet photons of H(, 2) has been measured. A MgF(, 2) window which allows the passage of VUV photon has been used. Several new series has been observed. The lifetime of VUV photons at three different energies has also been measured.

The radiative decay lifetimes for the a'('3)(SIGMA)('+)((nu) = 9,12-16) states of CO have been measured. The lifetimes, extrapolated to zero pressure for the (nu) = 12-16 vibrational levels have been found to be in the range of 4-5 (mu)sec and these results are consistent with a (nu)('3) extrapolation of previous lifetime measurements of the lower vibrational levels. The collisional quenching cross sections were calculated from the pressure dependence of the measured lifetimes.

Transmitted electron current spectrum for He and N(, 2) have been measured without modulating the electron gun and without using a phase sensitive detector. With this technique an instrumental resolution of 30 meV FWHM has been obtained.