Rydberg State Ionization by Half-Cycle-Pulse Excitation: Strong Kicks Create Slow Electrons

Abstract

The asymptotic velocity distribution of electrons ionized in half-cycle-pulse excitation of high Rydberg states (n=34), placed in a static electric field, is studied using electron velocity-map imaging. At weak half-cycle pulse strengths, the electrons escape over the saddle point in the potential. For strong half-cycle pulses, the electrons are emitted in the direction of the field kick. The much slower and less intense half cycle of opposite polarity, which necessarily follows the main half-cycle pulse, strongly affects the momentum distribution and reduces the excess energy of the electrons significantly.

Transitions Driven by a Missing Frequency

“…If the intensity of the light becomes very high, multiphoton transitions can become important, ultimately reaching the situation that the electric field of the light suppresses the binding Coulomb forces as happens, e.g., in above-threshold ionization [1,2] or in the interaction of Rydberg atoms with strong half-cycle electric field pulses [3][4][5][6]. In another class of light-matter interactions, for example, in stimulated Raman adiabatic passage, the coherent properties of light are employed [7].…”

“…Therefore, HCPs develop a long ''tail'' of opposite polarity during propagation such that in the far field, the integral of the electric field is zero. The effects of this impurity on Rydberg atom excitation have been investigated earlier [4,6,8] and are not the subject of this Letter. THz half-cycle pulses are being used for rotational spectroscopy of molecules in the gas phase [9,10].…”

All-optical control of unipolar pulse generation in a resonant medium with nonlinear field coupling

“…In particular, this property can be an advantage if one wants to control the ultrafast charge motion in the pump-probe experiments. Specifically, unipolar pulses can efficiently deliver a kinetic momentum to the charged particles in order to control their motion, for instance, to ionize the atoms or ions in the medium [5][6][7] or to measure the quantum dynamics of electron and ionic wavepackets [8][9][10][11]. Unipolar pulses can efficiently accelerate the charge particles and thus be used for producing coherent beams for particle injectors and charge-particle accelerating devices [12,13].…”

Generation of unipolar pulses in a circular Raman-active medium excited by few-cycle optical pulses

“…In contrast to conventional optical pulses which are bipolar, that is, Possession of this characteristic property makes unipolar pulses ideally suited for the control of charges dynamics in matter. Half-cycle pulses have been obtained experimentally in terahertz range [8][9][10] and have been used for the ionization and to produce novel dynamic states in Rydberg atoms [9,[11][12][13]. Unipolar half-cycle pulses can be produced experimentally when irradiating a double foil target with intense few-cycle laser pulses [14].…”