Suppression of multiphoton intrashell resonances in Li Rydberg atoms

Abstract

Multiphoton intrashell transitions in strongly driven Li (n = 25) Rydberg atoms are studied experimentally. Orthogonal dc electric and magnetic fields lift the degeneracy of the n shell and define the eccentricity e of the initial coherent elliptic states, which are formed by laser excitation and subsequent adiabatic transformation. The intrashell transitions are driven by a time-harmonic electric field linearly polarized parallel to the major axis of the ellipse. N -photon resonances with N = 1 − 9 are studied as a function of e. All resonances with N 3 are suppressed at certain e values in between 0 and 1. A similar system was analyzed by Yabuzaki et al. [Phys. Rev. A 10, 1955(1974] who found a simple pattern of suppressions that applies also for the present experiments. The results of these experimentally confirm that each time N is increased by two, an additional suppression is observed.

Unidentified transitions in one-photon intrashell dynamics in Rydberg atoms

“…For the dynamics of interest here, only the component of E s parallel to B is important. It causes a symmetric splitting of the resonances relative to the unperturbed position [17]. From observed splittings 4 ± 1 MHz the field is estimated to be 40 ± 10 mV/cm.…”

“…The experimental arrangement was used earlier by Waheed et al [17] who discussed it in detail. Here we repeat only what is important for the present discussion.…”

“…At t = 30 μs, when the selected atoms are in the middle of the rf region, a linearly polarized rf pulse is applied. The rf pulse has a Gaussian-like envelope with a full width at half maximum (FWHM) that could be varied from 1 to 5 μs and a maximum within the range 0-1.2 V/cm [17].…”

“…The formation of CESs in external fields was described in [2,3,8]. Intrashell dynamics of the Stark-Zeeman split n = 25 shell in Li was studied extensively over the last 10 years [9][10][11][12][13][14][15][16][17].…”

“…The major axis of the CES, E dc and E rf are parallel, and B is perpendicular to the orbital plane. E dc and B lift the degeneracy of the n shell giving rise to one and multiphoton transitions when a multiple of the rf frequency is near resonance with the Stark-Zeeman splitting of the shell [17]. A small stray electric field parallel to B splits the one-photon resonance into two, and the dynamics in between is studied by state-selective field ionization (SFI) [18][19][20].…”