Title: Propagating molecular rotational coherences through single-frequency pulses in the strong field regime

Abstract

In the weak-field limit in which microwave spectroscopy is typically carried out, an application of a single-frequency pulse that is resonant with a molecular transition will create a coherence between the pair of states involved in the rotational transition, producing a free-induction decay (FID) that, after Fourier transform, produces a molecular signal at that same resonance frequency.With the advent of chirped-pulse Fourier transform microwave methods, the high-powered amplifiers needed to produce broadband microwave spectra also open up other experiments that probe the molecular response in the high-field regime. This paper describes a series of experiments involving resonant frequency pulses interrogating jet-cooled molecules under conditions of sufficient power to Rabi oscillate the two-state system through many Rabi cycles. The Fourier-transformed FID shows coherent signal not only at the applied resonant frequency but also at a series of transitions initially connected to the original one by sharing an upper or lower level with it. As the duration of the single-frequency excitation is increased from 250 to 1500 ns, the number of observed off-resonant,but dipole-allowed, molecular coherences grow. The phenomenon is quite general, having been demonstrated in Z-phenylvinylnitrile, E-phenylvinylnitrile (E-PVN), benzonitrile, guaiacol, and 4-pentynenitrile. In E-PVN, the highest power/longest pulse duration, coherent signalmore » is also present at energetically nearby but not directly connected transitions. Even in molecular samples containing more than one independent species, only transitions due to the single species responsible for the original resonant transition are present. We develop a time-dependent model of the molecular/photon system and use it in conjunction with the experiment to test possible sources of the phenomenon.« less

Authors:

Hernandez-Castillo, A. O.  ^[1];

• Search DOE PAGES for author "Hernandez-Castillo, A. O."
• Search DOE PAGES for ORCID "0000-0001-7472-1044"
• Search orcid.org for ORCID "0000-0001-7472-1044"

Abeysekera, Chamara ^[2]; Robicheaux, F. ^[3]; Zwier, Timothy S.  ^[3]

• Search DOE PAGES for author "Zwier, Timothy S."
• Search DOE PAGES for ORCID "0000-0002-4468-5748"
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+ Show Author Affiliations

1. Purdue Univ., West Lafayette, IN (United States); Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin (Germany)
2. Purdue Univ., West Lafayette, IN (United States); Intel Corporation, Hillsboro, OR (United States)
3. Purdue Univ., West Lafayette, IN (United States)

Publication Date:

2019-08-28

Research Org.:

Purdue Univ., West Lafayette, IN (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES); USDOE Office of Science (SC), Basic Energy Sciences (BES). Chemical Sciences, Geosciences & Biosciences Division

OSTI Identifier:

1610307

Alternate Identifier(s):

OSTI ID: 1568918; OSTI ID: 1670702

Grant/Contract Number:  

FG02-96ER14656; SC0012193

Resource Type:

Accepted Manuscript

Journal Name:

Journal of Chemical Physics

Additional Journal Information:

Journal Volume: 151; Journal Issue: 8; Journal ID: ISSN 0021-9606

Publisher:

American Institute of Physics (AIP)

Country of Publication:

United States

Language:

English

Subject:

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; 74 ATOMIC AND MOLECULAR PHYSICS; chemistry; physics; Fourier transform spectroscopy; signal processing; microwave spectroscopy; transition moment; chemical compounds; coherence