Enhanced ionization of vibrational hot carbon disulfide molecules in strong femtosecond laser fields

Abstract

By using a heated molecular beam in combination with a time-of-flight mass spectrometer, we experimentally study the ionization of vibrational-hot carbon disulfide (CS 2 ) molecules irradiated by a linearly polarized 800-nm 50-fs strong laser field. The ion yields are measured in a laser intensity range of 7.0 × 10 12 W/cm 2 -1.5 × 10 14 W/cm 2 at different molecular temperatures of up to 1400 K. Enhanced ionization yield is observed for vibrationally excited CS 2 molecules. The results show that the enhancement decreases as the laser intensity increases, and exhibits non-monotonical dependence on the molecular temperature. According to the calculated potential energy curves of the neutral and ionic electronic states of CS 2 , as well as the theoretical models of molecular strong-field ionization available in the literature, we discuss the mechanism of the enhanced ionization of vibrational-hot molecules. It is indicated that the enhanced ionization could be attributed to both the reduced ionization potential with vibrational excitation and the Frank-Condon factors between the neutral and ionic electronic states. Our study paves the way to understanding the effect of nuclear motion on the strongfield ionization of molecules, which would give a further insight into theoretical and experimental investigations on the interaction of polyatomic molecules with strong laser fields.

Tunnel ionization of diatomic atmospheric gases (N2, O2) by laser radiation

“…The calculations were performed for N 2 and O 2 , and Values of parameters of the N 2 and O 2 molecules and of their positive ions. Here, ∆ is the energy of the electron excitation, R e is the equilibrium internuclear separation, ω e is the vibration fre quency for the molecule consisting of the 14 N or 16 O isotopes, and x e is the first anharmonicity constant. The data are taken from [21].…”

“…We introduced the notation ν fi = κ −1 fi in ( 16). The quantity (16) is the overlap integral between the core electronic states in the neutral molecule and in its ion. It can be found analytically in terms of the parameters produced Table 4.…”

“…Such a process (Stokesattenuated tun nel ionization), considered in [14], made it possible to explain the exper imental data concerning the ionization of the H 2 molecule [15]. A similar process, antiStokesenhanced tun nel ionization, was studied in [11,12] for diatomic molecules, which enabled a qualitative explanation of the experimental ionization probabilities of a vibrationally excited CS 2 mol ecule [16]. In addition, in a strong laser field, the deforma tion of molecules plays an important role.…”

Molecule opacity study on low-lying states of CS

“…CS molecule and sulfur-containing molecules in the stratosphere are also related to formation of sulfate aerosols, which may lead to acid rain effect and global climate change. [6] Hence, electronic structure and transition properties of the CS molecule have been continually arising interest in the past several decades.…”

Theoretical study of the radiative decay processes in H + (D + , T + )–Be collisions

“…The abundances of these light elements and the corresponding ratio supplies some meaningful information on the affection of a planetary companion in the formation and evolution of stars. [5][6][7][8][9][10] For fusion science, beryllium is treated as a primary wall material and hydrogen is treated as the main plasma constituent, hence, studies of the collision processes between beryllium and hydrogen are of great interest. [1] Since 2011, the JET experiment has been carried out through an ITER-like wall that is constituted of beryllium and tungsten.…”