Xenon-induced blue shift of thulium absorption lines

V. D. Vedenin

Wanda R. Ferrell, M. G. Payne, W. R. Garrett

Three-photon excitation and multiphoton ionization techniques have been used to measure self-broadening for several resonance lines in xenon and krypton. Tabulations of widths and shifts of the xenon lines at 146.9, 129.6, 119.2, and 117.0 nm were made for pressures between 50 and 900 Torr. Similar measurements were made for the krypton resonance line at 116.5 nm. For pressures less than 500 Torr the widths were found to be in reasonable agreement with theoretical results, which were extrapolated into regions of concentration where the criteria for their validity are at best questionable. We have also found the lines to be shifted to the high-energy side of the unperturbed line. For four of the five lines studied, the blue shifts increased nearly linearly with increasing pressure. In the four cases where the shift could be measured the ratio of shift to width was close to (1/2. Our experimental technique is very simple, but it has yielded what we believe to be the first resonance broadening data based on absorption under conditions where there is strong trapping of the resonance radiation.

P. Laporte, Nicole Damany, Henri Damany

Absorption spectra of high-density pure krypton and xenon gases, in the wavelength range 118-150 nm and the density range 1-80 amagat, exhibit a red shift of all the atomic lines. The shifts are interpreted by taking into account the high-density interactions with the help of the local field correction of Lorentz introduced in classical dispersion theory.

L. Esterowitz, J. Noonan, Alfons Schnitzler

Saswata Ghosh, Swapan Mandal

The optical Bloch equations of a four-level atomic system with three closely spaced upper levels irradiated by a single mode of the electromagnetic radiation field are constructed. Under the rotating wave approximation and by using the slowly varying envelope approximation, we obtain the analytical solution to these optical Bloch equations. These solutions, which are obtained perturbatively, are used to calculate the polarization and hence the absorptive line shape. In particular, we examine the effects of the field-induced coherence arising from the interference between the probability amplitudes of the levels participating in dipole-allowed transitions. We obtain the shifts of the resonance peak positions due to two different reasons. The first is due to the nonlinear effects arising from the closely spaced nature of the peaks. The second is attributed to the field-induced coherence alone. It is found that the shifts of the positions of the resonance peaks due to field-induced coherence may be in the blue or in the red region.

Motowo Tsukakoshi, Kōichi Shimoda