Coherent superposition of M-states in a single rovibrational level of H2 by Stark-induced adiabatic Raman passage

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Ultracold molecules offer unprecedented opportunities for the controlled interrogation of molecular events, including chemical reactivity in the ultimate quantum regime. The proliferation of methods to create, cool, and confine them has allowed the investigation of a diverse array of molecular systems and chemical reactions at temperatures where only a single partial wave contributes. Here we present a brief account of recent progress on the experimental and theoretical fronts on cold and ultracold molecules and the opportunities and challenges they provide for a fundamental understanding of bimolecular chemical reaction dynamics. Published by AIP Publishing. [http://dx

Section: B Quasiresonant Rotational and Vibrational Transfer In Molementioning

confidence: 99%

Perspective: Ultracold molecules and the dawn of cold controlled chemistry

Balakrishnan

2016

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271

“…More detailed descriptions of SARP can be found elsewhere. [16][17][18]38 The pump pulse is obtained from the second harmonic of an injection-seeded, Q-switched Nd 3+ :YAG laser (PRO-290, Spectra-Physics), and the Stokes pulse is derived from a pulsed dye amplifier (PrecisionScan, Sirah) which is seeded by a frequency stabilized ring dye laser (Matisse, Sirah) and pumped by the same Nd 3+ :YAG laser used to generate the pump pulse. All of our Nd 3+ :YAG lasers operate synchronously with the pulsed valve at a repetition rate of 20 Hz.…”

Section: Experimental Methodsmentioning

confidence: 99%

“…15 Using a pair of partially overlapping nanosecond pulses, SARP transfers nearly the entire population of the (v = 0, j = 0) ground state to the desired rovibrationally excited target state and simultaneously prepares the molecules in a single or superposition of specific m states. [16][17][18] Control over the external or orbital state of the colliding partners was achieved by coexpanding the two gases in the same molecular beam, which defined both the magnitude and direction of the collision velocity in the lab frame. 19,20 This technique ensured that only a few orbital states contributed to the collision by substantially reducing the HD-He relative speed (collision temperature).…”

Section: Article Scitationorg/journal/jcpmentioning

confidence: 99%

HD (v = 1, j = 2, m) orientation controls HD–He rotationally inelastic scattering near 1 K

Perreault

Mukherjee

Zare

2019

Self Cite

ARTICLEscitation.org/journal/jcp HD (v = 1, j = 2, m ) orientation controls HD-He rotationally inelastic scattering near 1 K ABSTRACT To investigate how molecular orientations affect low energy scattering, we have studied the rotational relaxation of HD (v = 1, j = 2, m) → (v ′ = 1, j ′ = 0) by collision with ground-state He, where v, j, and m designate the vibrational, rotational, and magnetic quantum numbers, respectively. We experimentally probed different collision geometries by preparing three specific m sublevels, including an m entangled sublevel, belonging to a single rovibrational (v = 1, j = 2) energy level within the ground electronic state of HD using Stark-induced adiabatic Raman passage. Low collision energies (0-5 K) were achieved by coexpanding a 1:19 HD:He mixture in a highly collimated supersonic beam, which has defined the direction of the collision velocity and restricted the incoming orbital angular momentum states, defined by the quantum number l, to l ≤ 2. Partial wave analysis of experimental data shows that a single l = 2 input orbital dominates the scattered angular distribution, implying the presence of a collisional resonance. The differential scattering angular distribution exhibits a greater than fourfold stereodynamic preference for the m = 0 input state vs m = ±2, when the quantization axis is oriented parallel to the collision velocity.Published under license by AIP Publishing. https://doi.ARTICLE scitation.org/journal/jcp FIG. 5. HD-He stereodynamics. The red, green, and blue curves give the scattering angular distribution dσ/dθ calculated using the scattering amplitudes shown in Tables I and II produced by HD (v = 1, j = 2, m) → (v ′ = 1, j ′ = 0) scattering for m = 0 (red curve), ±1 (green curve), ±2 (blue curve). Note that the angular distribution of HD (v = 1, j = 2, m = 0) is divided by 4, showing that it most efficiently scatters into the final (v ′ = 1, j ′ = 0) state.

“…2 In previous work we used SARP to transfer nearly 100% of the population in H 2 (v = 0, J = 0) to H 2 (v = 1, J = 0) in a beam of molecular hydrogen (H 2 ). [3][4][5] We report here the nearly complete population transfer of HD (v = 0, J = 0) to HD (v = 4, J = 0) in a supersonically expanded beam of pure HD, which shows the generality of this method to prepare isolated molecules, polar and nonpolar, in specific quantum states of high internal energy. In what follows, we describe in detail the specific preparation of HD (v = 4), but the reader should keep in mind that other molecules can be prepared in other high-lying vibrational levels with the availability of suitable laser sources.…”

Section: Introductionmentioning

confidence: 71%

Preparation of a selected high vibrational energy level of isolated molecules

Perreault

Mukherjee

Zare

2016

Self Cite

Stark induced adiabatic Raman passage (SARP) allows us to prepare an appreciable concentration of isolated molecules in a specific, high-lying vibrational level. The process has general applicability, and, as a demonstration, we transfer nearly 100 percent of the HD (v = 0, J = 0) in a supersonically expanded molecular beam of HD molecules to HD (v = 4, J = 0). This is achieved with a sequence of partially overlapping nanosecond pump (355 nm) and Stokes (680 nm) single-mode laser pulses of unequal intensities. By comparing our experimental data with our theoretical calculations, we are able to draw two important conclusions: (1) using SARP a large population (>10 molecules per laser pulse) is prepared in the (v = 4, J = 0) level of HD and (2) the polarizability α (≅0.6 × 10 C m V) for the (v = 0, J = 0) to (v = 4, J = 0) Raman overtone transition is only about five times smaller than α for the (v = 0, J = 0) to (v = 1, J = 0) fundamental Raman transition. Moreover, the SARP process selects a specific rotational level in the vibrational manifold and can prepare one or a phased linear combination of magnetic sublevels (M states) within the selected vibrational-rotational level. This capability of preparing selected, highly excited vibrational levels of molecules under collision-free conditions opens new opportunities for fundamental scattering experiments.