Production of rotationally cold methyl radicals in pulsed supersonic beams

Grzesiak, Jonas; Vashishta, Manish; Djuricanin, Pavle; Stienkemeier, F.; Mudrich, M.; Dulitz, Katrin; Momose, Takamasa

doi:10.1063/1.5052017

Cited by 15 publications

(19 citation statements)

References 37 publications

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“…The second beam containing the reaction partner of the deflected molecular species is generated by a solenoid-based pulsed valve. 75 For the production of internally cold and dense beams of radicals or metastable rare gas atoms, this valve was combined with either a dielectric barrier discharge (DBD) or a plate discharge 76 based on the design of Ref. 77.…”

Section: B Metastable-atom and Radical Sourcementioning

confidence: 99%

A novel crossed-molecular-beam experiment for investigating reactions of state- and conformationally selected strong-field-seeking molecules

et al. 2021

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The structure and quantum state of the reactants have a profound impact on the kinetics and dynamics of chemical reactions. Over the past years, significant advances have been made in the control and manipulation of molecules with external electric and magnetic fields in molecular-beam experiments for investigations of their state-, structure-and energy-specific chemical reactivity. Whereas studies for neutrals have so far mainly focused on weak-field-seeking species, we report here progress towards investigating reactions of strong-field-seeking molecules by introducing a novel crossed-molecular-beam experiment featuring an electrostatic deflector. The new setup enables the characterisation of state-and geometry-specific effects in reactions under single-collision conditions. As a proof of principle, we present results on the chemi-ionisation reaction of metastable neon atoms with rotationally state-selected carbonyl sulfide (OCS) molecules and show that the branching ratio between the Penning and dissociative ionisation pathways strongly depends on the initial rotational state of OCS.

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Section: B Metastable-atom and Radical Sourcementioning

confidence: 99%

A novel crossed-molecular-beam experiment for investigating reactions of state- and conformationally selected strong-field-seeking molecules

et al. 2021

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“…The supersonic beam is generated by a high-intensity, short-pulse solenoid valve (CRUCS, d = 100 µm orifice diameter, 40 • cone, copper body) whose characteristics are described in Ref. [36]. The temperature of the valve is controlled by a cryocooler (CTI, 350CP) whose temperature is typically regulated to a set value with accuracy to within 0.1 K using proportional-integral-derivative (PID)-controlled resistive heating (LakeShore Model 325).…”

Section: A Vacuum Apparatusmentioning

confidence: 99%

“…1) is placed inside a third chamber. Since their relative distance is accurately known (224.5±0.5 mm), the longitudinal velocity of the supersonic beam of metastable helium atoms can be inferred from the difference ∆t of the time-of-flight signal intensities at the two detectors [36].…”

Section: A Vacuum Apparatusmentioning

confidence: 99%

Optical Quenching of Metastable Helium Atoms using Excitation to the 4P State

et al. 2019

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Discharge and electron-impact excitation lead to the production of metastable helium atoms in two metastable states, 2 1 S 0 and 2 3 S 1 . However, many applications require pure beams of one of these species or at least a detailed knowledge of the relative state populations. In this paper, we present the characterization of an original experimental scheme for the optical depletion of He(2 1 S 0 ) in a supersonic beam which is based on the optical excitation of the 4 1 P 1 ← 2 1 S 0 transition at 397 nm using a diode laser. From our experimental results and from a comparison with numerical calculations, we infer a near unit depletion efficiency at all beam velocities under study (1070 m/s ≤ v ≤ 1750 m/s). Since the technique provides a direct means to determine the singlet-to-triplet ratio in a pulsed supersonic helium beam, our results show that the intrabeam singlet-to-triplet ratio is different at the trailing edges of the gas pulse.

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“…Overall, our work systematically explores optical and THz-pulse induced alignment and orientation as a function of both intrinsic molecular parameters (polarizability, rotational constants and nuclear spin statistics, as obtained from quantum chemistry simulations) and experimental parameters (laser intensity, pulse duration, frequency, CEP, and temperature of the molecular sample), with particular attention towards parameters that reflect typical conditions in the laboratory. The improved state-of-the-art molecular beams produced by supersonic expansions through valves of the Even Lavie type helps in achieving rotational temperature as low as 2K 43 and hence, presents an unique opportunity to achieve high alignment for symmetric top molecules with non-resonating single pulse, and for exploring the fundamental of excitation dynamics. Control over oriented higher angular momentum states in a preferential direction by means of laser-induced rotational excitation is the first crucial step towards manipulating the molecular-axis distribution, thereby manipulating further molecular processes.…”

Section: Discussionmentioning

confidence: 99%

Manipulation of Rotational States With Varying Pulse Parameter: Achieving High Molecular Alignment and Orientation for CH3F

Chordiya

Simkó

Szidarovszky

et al. 2022

Preprint

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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 (AnO). In this work, we examine the critical role of different pulse parameters on the field-free AnO dynamics of the CH3F molecule, and identify experimentally feasible optical and THz range laser parameters that ensure maximal AnO 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 distributions, the origin of specific AnO dynamics was addressed. We could identify two qualitatively different AnO behaviors and revealed their connection with the pulse parameters and the population of excited rotational states. We report here the highest alignment of ⟨cos2θ⟩=0.843 andorientation of⟨cos(θ)⟩=0.886 for CH3F molecule at 2K using 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 AnO in laboratory conditions for advanced applications.

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Production of rotationally cold methyl radicals in pulsed supersonic beams

Cited by 15 publications

References 37 publications

A novel crossed-molecular-beam experiment for investigating reactions of state- and conformationally selected strong-field-seeking molecules

A novel crossed-molecular-beam experiment for investigating reactions of state- and conformationally selected strong-field-seeking molecules

Optical Quenching of Metastable Helium Atoms using Excitation to the 4P State

Manipulation of Rotational States With Varying Pulse Parameter: Achieving High Molecular Alignment and Orientation for CH3F

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