Cooling of large molecules below 1 K and He clusters formation

Even, U.; Jortner, Joshua; Noy, D.; Lavie, N.; Cossart‐Magos, Claudina

doi:10.1063/1.481405

Cited by 570 publications

(432 citation statements)

References 14 publications

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“…A gas mixture of ∼10 mbar carbonyl sulfide (OCS) and 10 bar of Ne is expanded supersonically into vacuum through an Even-Lavie valve [34,35], forming a pulsed molecular beam. The molecular beam is skimmed twice before entering a 15-cm-long electrostatic deflector that spatially disperses the molecular beam in the vertical direction according to the quantum states populated [29,30].…”

Section: Experimental Methodsmentioning

confidence: 99%

Ionization of oriented carbonyl sulfide molecules by intense circularly polarized laser pulses

et al. 2011

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We present combined experimental and theoretical results on strong-field ionization of oriented carbonyl sulfide molecules by circularly polarized laser pulses. The obtained molecular frame photoelectron angular distributions show pronounced asymmetries perpendicular to the direction of the molecular electric dipole moment. These findings are explained by a tunneling model invoking the laser-induced Stark shifts associated with the dipoles and polarizabilities of the molecule and its unrelaxed cation. The focus of the present article is to understand the strong-field ionization of one-dimensionally-oriented polar molecules, in particular asymmetries in the emission direction of the photoelectrons. In the following article [Phys. Rev. A 83, 023406 (2011)] the focus is to understand strong-field ionization from three-dimensionally-oriented asymmetric top molecules, in particular the suppression of electron emission in nodal planes of molecular orbitals.

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Section: Experimental Methodsmentioning

confidence: 99%

Ionization of oriented carbonyl sulfide molecules by intense circularly polarized laser pulses

et al. 2011

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“…The beam of He* is generated by expanding a pulse of neat He atoms into vacuum using a modified Even-Lavie valve (ELV) [49] that is cooled to about 16 K using a commercially available cold head (Oerlikon Leybold). At this temperature, the mean thermal velocity of helium is about 460 m/s.…”

Section: B Metastable Helium Beammentioning

confidence: 99%

Multistage Zeeman decelerator for molecular-scattering studies

Cremers¹,

Chefdeville²,

Janssen³

et al. 2017

Phys. Rev. A

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We present a concept for a multistage Zeeman decelerator that is optimized particularly for applications in molecular beam scattering experiments. The decelerator consists of a series of alternating hexapoles and solenoids, that effectively decouple the transverse focusing and longitudinal deceleration properties of the decelerator. It can be operated in a deceleration and acceleration mode, as well as in a hybrid mode that makes it possible to guide a particle beam through the decelerator at constant speed. The deceleration features phase stability, with a relatively large six-dimensional phase-space acceptance. The separated focusing and deceleration elements result in an unequal partitioning of this acceptance between the longitudinal and transverse directions. This is ideal in scattering experiments, which typically benefit from a large longitudinal acceptance combined with narrow transverse distributions. We demonstrate the successful experimental implementation of this concept using a Zeeman decelerator consisting of an array of 25 hexapoles and 24 solenoids. The performance of the decelerator in acceleration, deceleration, and guiding modes is characterized using beams of metastable helium ( 3 S) atoms. Up to 60% of the kinetic energy was removed for He atoms that have an initial velocity of 520 m/s. The hexapoles consist of permanent magnets, whereas the solenoids are produced from a single hollow copper capillary through which cooling liquid is passed. The solenoid design allows for excellent thermal properties and enables the use of readily available and cheap electronics components to pulse high currents through the solenoids. The Zeeman decelerator demonstrated here is mechanically easy to build, can be operated with cost-effective electronics, and can run at repetition rates up to 10 Hz.

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“…In this context we note that our explanation for the experimental observations could be tested by experiments using expansion conditions that produce a colder internal distribution for NO-Ar. Such an experiment could be undertaken using, for example, a very high pressure pulsed valve such as the Evan-Lavie design, 27 although care would be required to ensure that NO-Ar remained the dominant species.…”

Section: G Consistency With Previous Measurementsmentioning

confidence: 99%

The dissociation of NO–Ar(Ã) from around threshold to 200 cm−1 above threshold

Holmes-Ross

Lawrance

2010

The Journal of Chemical Physics

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We report an investigation of the dissociation of Ã state NO-Ar at energies from 23 cm −1 below the dissociation energy to 200 cm −1 above. The NO product rotational distributions show population in states that are not accessible with the energy available for excitation from the NO ground state. This effect is observed at photon energies from below the dissociation energy up to approximately 100 cm −1 above it. Translational energy distributions, extracted from velocity map images of individual rotational levels of the NO product, reveal contributions from excitation of high energy NO-Ar X states at all the excess energies probed, although this diminishes with increasing photon energy and is quite small at 200 cm −1 , the highest energy studied. These translational energy distributions show that there are contributions arising from population in vibrational levels up to the X state dissociation energy. We propose that the reason such sparsely populated levels contribute to the observed dissociation is a considerable increase in the transition moment, via the FranckCondon factor associated with these highly excited states, which arises because of the quite different geometries in the NO-Ar X and Ã states. This effect is likely to arise in other systems with similarly large geometry changes.

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Cooling of large molecules below 1 K and He clusters formation

Cited by 570 publications

References 14 publications

Ionization of oriented carbonyl sulfide molecules by intense circularly polarized laser pulses

Ionization of oriented carbonyl sulfide molecules by intense circularly polarized laser pulses

Multistage Zeeman decelerator for molecular-scattering studies

The dissociation of NO–Ar(Ã) from around threshold to 200 cm−1 above threshold

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