Spectrum of quasistable states in a strong microwave field

Abstract

When atoms are exposed to intense laser or microwave pulses ∼ 10% of the atoms are found in Rydberg states subsequent to the pulse, even if it is far more intense than required for static field ionization. The optical spectra of the surviving Li atoms in the presence of a 38 GHz microwave field suggest how atoms survive an intense pulse. The spectra exhibit a periodic train of peaks 38 GHz apart. One peak is just below the limit, and with a 90 V/cm field amplitude the train extends from 300 GHz above the limit to 3000 GHz below it. The spectra and quantum mechanical calculations imply that the atoms survive in quasi stable states in which the Rydberg electron is in a weakly bound orbit infrequently returning to the ionic core during the intense pulse.

Coherence, ionization, and recombination in a microwave field

“…The notion that multiple field cycles are important is the motivation for Floquet approaches to this and similar problems [6,[21][22][23]. Further support for a Floquet approach comes from frequency domain experiments, in which series of peaks above the limit, separated by the microwave frequency, were observed [7,14,18], as well as from the phase dependence reported here. Since the amplitude modulated laser field has only two optical frequency components, the relation between the relative phases of the two optical components at ω 0 ± ω and the phase of the envelope is particularly simple.…”

“…The control of stray fields is more critical for low microwave frequencies [18], so we chose the highest frequency allowed by the bandwidth of the photodiode used in the locking system. To minimize stray fields we measure the field dependent depression of the ionization limit by scanning one of 819 nm lasers.…”

Production of φ Mesons on Nuclear Targets in the Quark–Gluon String Model

“…[8], and the fragmentation functions of quarks and diquarks into ϕ-meson are presented in ref. [14].…”

“…The QGSM description of the production of secondary pseudoscalar mesons π and K, and of baryons p, p, Λ, and Λ, was obtained many years ago in [7,8,9,10]. Vector meson production was considered in [11,12,13,14]. The yields of hyperons, including the multistrange ones, has been described in [15,16].…”

“…Already in the paper [14] we had for the first time applied the QGSM formalism to the description of the spectra of vector ϕ-mesons production in πp and pp collisions, and of the ratios of yields ϕ/π − and ϕ/K − in pp collisions for a large scope of the initial energy, going up to the RHIC and LHC ranges.…”