Line shapes of atomic transitions in excited dense gas

Abstract

We discuss recently published results of experimental studies of dipole-dipole broadened line shapes in excited atomic vapors. The Lorentz local-field shift and self-broadened width were measured in optically excited potassium and rubidium vapors. Strong reduction of the shift and width was observed. This effect allowed resolve electromagnetically induced dressed states inside the self-broadened spectral profile. The experimental results were interpreted using well-known models of the dipole-dipole interactions.Intensity, arb. units Frequency modulated reflection spectra of a potassium vapor at atomic density N = 4.9×10 17 cm −3 measured on the D 1 transition. Curve (1) presents the linear reflection spectrum. Curve (2) shows the narrow Autler-Townes components (corresponding dressed states) when pump laser tuned to D2 transition. The zero on the frequency axis refers to the center frequency of the absorption spectrum of a low density vapor (Doppler width ≈ 1 GHz). The red arrow indicates frequency of the pump laser

Non-Dicke decay in a small spherical sample with radially varying density

“…The eigenfunctions and eigenvalues are the same as calculated here, but the time development of each mode follows exp(λt) instead of exp(−λt). (The Lorentz shift is also reversed [12,13]. )…”

Hyperfine dipole-dipole broadening of selective reflection spectroscopy at the gas-solid interface

“…Thus it is meaningful to reduce the dipole-dipole broadening. In the range 10 16 -10 17 cm −3 , the dipole-dipole broadening is much larger than Doppler broadening and has been investigated widely [7,10,[15][16][17][18] based on SR spectroscopy. The reduction of spectral width caused by dipole-dipole interaction has been observed in rubidium [17] and potassium [18] (a) E-mail: zhaoyt@sxu.edu.cn with high density.…”

Selective reflection technique as a probe to monitor the growth of metallic thin film on dielectric surfaces

“…Pressure-induced homogeneous broadening and frequency shift also change the atomic polarization. Therefore, the observation of the reflected intensity of a laser scanned around the atomic resonance can be used to measure the collisional pressure broadening [18,19] and the van der Waals coefficient for excited short-lived levels [14][15][16].…”

“…The technique was used, for instance, (i) to measure the van der Waals (vW) atom-surface interaction for atomic short-lived excited states [14,15]; (ii) to measure resonant effects between atomic transitions and surface polariton modes that might change the vW interaction into repulsive [16] or induce a surface temperature dependence of the vW force [17]; (iii) to probe linewidth modifications due to atom-atom collisions [18,19]. Furthermore, the SR lineshape is modified if an intermediary layer is introduced between the substrate and the vapor [20,21] and this reflection technique has therefore been suggested as an adequate tool to probe films thickness in such structures.…”