Laser-induced fluorescence measurements of resonance broadening in xenon

Resonance broadening in atomic xenon has been studied by using laser-induced fluorescence of two excited-state electronic transitions. The impact theory result for resonance broadening is verified to be accurate and the onset of the breakdown of the theory is chronicled. The spectral broadening of the 6s[3/2](0)(1)(P-3(1))-->6p[1/2](0) (828-nm) transition by the resonant interaction of its lower level with ground-state xenon was investigated for densities of 4X10(21)-2X10(24) atoms m(-3). The predominantly Doppler-broadened 6s[3/2](0)(2)(P-3(2))-->6p[3/2](2) (823-nm) transition was analyzed for similar conditions, primarily to establish the kinetic temperature of the neutral xenon. Tunable narrow-linewidth semiconductor diode lasers were used to probe the excited states, which were produced by a direct-current glow discharge. The intricate hyperfine structure of the measured profiles was taken into account by summing constituent Voigt profiles to construct model line shapes. The 6s[3/2](0)(1)-->6p[1/2](0) broadening constant at low densities and at 311 K was found to be 6.04(+/-0.66)X10(-21) MHz m(3) atom(-1). This result is in agreement with the value predicted by the impact theory for resonance broadening. The 6s[3/2](0)(1) -->6p[1/2](0) Lorentzian width extrapolated to zero density, 43 +/- 15 MHz, is in accord with the natural linewidth. At densities above 6X10(23) atoms m(-3) the recorded line shapes of this transition exhibited an asymmetry, providing clear evidence of the breakdown of the impact approximation. The measured Lorentzian broadening for the 6s[3/2](0)(2)-->6p[3/2](2) transition was 8.3(+/-1.8)X10(-22) MHz m(3) atom(-1) at 311 K.