Collisional effects on xenon 6p fluorescence
M. Rankin, Jon P. Davis, Christopher Giranda +1 more
We describe collision studies on the two-photon excitation and fluorescence of the xenon 6p[1/2,0] excited state. Molecular nitrogen is the major collision partner. The 250-nm second harmonic of a line-narrowed Hansch-type dye laser excites the 6p state of xenon by two-photon absorption. Sample mixtures contain xenon at a partial pressure of 1 Torr and nitrogen at partial pressures of up to several hundred Torr. Time-resolved and time-integrated measurements of the intensity of the 828-nm 6p[1/2,0]—6s[3/2,1] allowed transition are obtained with photomultipliers, a transient digitizer, and a computerized data acquisition system. We extract pressure-dependent and pressure-independent components of the fluorescence lifetime and fluorescence yield from measurements over a range of nitrogen pressures. When the excitation power density is of the order of 104 W/cm2, the excited xenon atoms decay spontaneously. For spontaneous fluorescence, we obtain an inelastic (quenching) collision cross section of ~10–14 cm2 for xenon-nitrogen collisions, and a pressure-broadening coefficient of ~3 × 107 Hz/(Torr N2) for the two-photon transition rate. For excitation intensities above 2.6 × 106 W/cm2, the xenon atoms radiate cooperatively in a subnanosecond pulse. The fluorescence yield of this cooperative emission increases with nitrogen pressure rather than decreasing as in the spontaneous case. Mechanisms are discussed.
Annual Meeting Optical Society of America•Jan 1, 1986•0 citations