Achieving high molecular alignment and orientation for CH$$_3$$F through manipulation of rotational states with varying optical and THz laser pulse parameters

Abstract

Increasing interest in the fields of high-harmonics generation, laser-induced chemical reactions, and molecular imaging of gaseous targets demands high molecular “alignment” and “orientation” (A&O). In this work, we examine the critical role of different pulse parameters on the field-free A&O dynamics of the CH$$_3$$ 3 F molecule, and identify experimentally feasible optical and THz range laser parameters that ensure maximal A&O for such molecules. Herein, apart from rotational temperature, we investigate effects of varying pulse parameters such as, pulse duration, intensity, frequency, and carrier envelop phase (CEP). By analyzing the interplay between laser pulse parameters and the resulting rotational population distribution, the origin of specific A&O dynamics was addressed. We could identify two qualitatively different A&O behaviors and revealed their connection with the pulse parameters and the population of excited rotational states. We report here the highest alignment of $$\langle {\mathrm{cos}^2\theta }\rangle = 0.843$$ ⟨ cos 2 θ ⟩ = 0.843 and orientation of $$\langle {\mathrm{cos}(\theta )}\rangle = 0.886$$ ⟨ cos ( θ ) ⟩ = 0.886 for CH$$_3$$ 3 F molecule at 2 K using a single pulse. Our study should be useful to understand different aspects of laser-induced unidirectional rotation in heteronuclear molecules, and in understanding routes to tune/enhance A&O in laboratory conditions for advanced applications.

From chiral laser pulses to femto- and attosecond electronic chirality flips in achiral molecules

“…The present chirality flips should then modulate the CISS signals on the fs to as time scale, analogous to the switches of the direction of spinpolarization induced by chirality flips during the rotation of a molecular motor 49 . The effects will be reduced by finite orientation (imperfect axis distribution) [13][14][15][16]50,51 . By extrapolation of the abstract of (Ref.…”

“…For the derivation, let us first set the stage. The effect is demonstrated here by means of quantum dynamics simulations for the molecule NaK which has been pre-oriented by z-polarized THz and femtosecond lasers pulses; [13][14][15] the details are in the Supplementary Information (SI). For reference, we shall assume perfect pre-orientation even though this cannot be achieved in practice 16 .…”

Microscopic theory of Raman scattering for the rotational organic cation in metal halide perovskites

“…Based on angular momentum exchange between photon and rotational particles, quantum control of the rotational atoms or molecules by laser have been studied both theoretically and experimentally in areas of atomic, molecular and optical physics as well as in physical chemistry [17][18][19][20]. While the corresponding studies on ROC in perovskite materials are still very few.…”

Impact of Structural Modifications on Ultrafast Correlation-Driven Charge Migration in Organic Molecules: For Molecular Engineering

“…We have presented our results on the use of THz pulse to study alignment and orientation dynamics in the CH 3 X molecule in the Ref. [212,224].…”

“…Note that all figures, results and discussions presented in this chapter are adapted with permission from Ref. [212], Copyright © (2022), Kalyani Chordiya et al…”