Applications of Fourier transform microwave (FTMW) detected infrared–microwave double-resonance spectroscopy to problems in vibrational dynamics

Douglass, Kevin O.; Johns, James E.; Nair, Pradeep M.; Brown, Gordon G.; Rees, Frances S.; Pate, Brooks H.

doi:10.1016/j.jms.2006.05.015

Cited by 14 publications

(3 citation statements)

References 83 publications

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“…Due to the strong internal rotor effects present in the spectrum of trans-methyl formate, FTMW-MW double resonance measurements played a crucial role in confirming the spectral assignments reported here and in locating new transitions. The use of an FTMW cavity spectrometer for double resonance measurements has been previously described (Nakajima et al 2002;Suma et al 2004;Douglass et al 2006). In this experiment, the FTMW cavity is tuned to a rotational transition.…”

Section: Methodsmentioning

confidence: 99%

Laboratory and Tentative Interstellar Detection of Trans-Methyl Formate Using the Publicly Available Green Bank Telescope Primos Survey

Neill

Muckle

Zaleski

et al. 2012

ApJ

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102

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The rotational spectrum of the higher-energy trans conformational isomer of methyl formate has been assigned for the first time using several pulsed-jet Fourier transform microwave spectrometers in the 6-60 GHz frequency range. This species has also been sought toward the Sagittarius B2(N) molecular cloud using the publicly available PRIMOS survey from the Green Bank Telescope. We detect seven absorption features in the survey that coincide with laboratory transitions of trans-methyl formate, from which we derive a column density of 3.1 (+2.6, -1.2) × 10 13 cm -2 and a rotational temperature of 7.6 ± 1.5 K. This excitation temperature is significantly lower than that of the more stable cis conformer in the same source but is consistent with that of other complex molecular species recently detected in Sgr B2(N). The difference in the rotational temperatures of the two conformers suggests that they have different spatial distributions in this source. As the abundance of trans-methyl formate is far higher than would be expected if the cis and trans conformers are in thermodynamic equilibrium, processes that could preferentially form trans-methyl formate in this region are discussed. We also discuss measurements that could be performed to make this detection more certain. This manuscript demonstrates how publicly available broadband radio astronomical surveys of chemically rich molecular clouds can be used in conjunction with laboratory rotational spectroscopy to search for new molecules in the interstellar medium.

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Section: Methodsmentioning

confidence: 99%

Laboratory and Tentative Interstellar Detection of Trans-Methyl Formate Using the Publicly Available Green Bank Telescope Primos Survey

Neill

Muckle

Zaleski

et al. 2012

ApJ

Self Cite

102

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“…2. Based on previous work using an FTMW cavity spectrometer to detect UV 26 and IR 27 absorption, the coherence-converted population transfer (CCPT) technique 28 has been developed to detect laser absorption background-free and will be described briefly here.…”

Section: B Uv-ftmw Double Resonance Spectroscopymentioning

confidence: 99%

Next generation techniques in the high resolution spectroscopy of biologically relevant molecules

Neill

Douglass

Pate

et al. 2011

Phys. Chem. Chem. Phys.

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Recent advances in the technology of test and measurement equipment driven by the computer and telecommunications industries have made possible the development of a new broadband, Fourier-transform microwave spectrometer that operates on principles similar to FTNMR. This technique uses a high sample-rate arbitrary waveform generator to construct a phase-locked chirped microwave pulse that gives a linear frequency sweep over a wide frequency range in 1 μs. The chirped pulse efficiently polarizes the molecular sample at all frequencies lying within this band. The subsequent free induction decay of this polarization is measured with a high-speed digitizer and then fast Fourier-transformed to yield a broadband, frequency-resolved rotational spectrum, spanning up to 11.5 GHz and containing lines that are as narrow as 100 kHz. This new technique is called chirped-pulse Fourier transform microwave (CP-FTMW) spectroscopy. The technique offers the potential to determine the structural and dynamical properties of very large molecules solely from fully resolved pure rotational spectra. FTMW double resonance techniques employing a low-resolution UV laser facilitate an easy assignment of overlapping spectra produced by different conformers in the sample. Of particular interest are the energy landscapes of conformationally flexible molecules of biological importance, including studies of their interaction with solvent and/or other weakly bound molecules. An example is provided from the authors' work on p-methoxyphenethylamine, a neurotransmitter, and its complexes with water.

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“…Many experiments utilizing double resonance have been conducted across a wide range of wavelengths, which include radio–microwave, , microwave–microwave, − microwave–millimeter, − microwave–infrared, − microwave–optical, − microwave–ultraviolet, , microwave–X-ray, millimeter–infrared, millimeter–optical, − infrared–infrared, − infrared–optical, infrared–ultraviolet, − infrared–X-ray, optical–optical, − optical–ultraviolet, ultraviolet–ultraviolet, , ultraviolet–X-ray, and phosphorescence–microwave. , Of these previously conducted experiments, it is most relevant to focus on the five previous works reporting microwave–millimeter double resonance. Three of these experiments were conducted by Endo and co-workers, ,, while the other two were conducted by Jäger and co-workers. , These double-resonance experiments were conducted with point-by-point scans, instead of using a chirp or a sweep modulation to achieve broadband coverage.…”

Section: Introductionmentioning

confidence: 99%

AC Stark Effect Observed in a Microwave–Millimeter/Submillimeter Wave Double-Resonance Experiment

et al. 2018

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Microwave-millimeter/submillimeter wave double-resonance spectroscopy has been developed with the use of technology typically employed in chirped pulse Fourier transform microwave spectroscopy and fast-sweep direct absorption (sub)millimeter-wave spectroscopy. This technique offers the high sensitivity provided by millimeter/submillimeter fast-sweep techniques with the rapid data acquisition offered by chirped pulse Fourier transform microwave spectrometers. Rather than detecting the movement of population as is observed in a traditional double-resonance experiment, instead we detected the splitting of spectral lines arising from the AC Stark effect. This new technique will prove invaluable when assigning complicated rotational spectra of complex molecules. The experimental design is presented along with the results from the double-resonance spectra of methanol as a proof-of-concept for this technique.

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Applications of Fourier transform microwave (FTMW) detected infrared–microwave double-resonance spectroscopy to problems in vibrational dynamics

Cited by 14 publications

References 83 publications

Laboratory and Tentative Interstellar Detection of Trans-Methyl Formate Using the Publicly Available Green Bank Telescope Primos Survey

Laboratory and Tentative Interstellar Detection of Trans-Methyl Formate Using the Publicly Available Green Bank Telescope Primos Survey

Next generation techniques in the high resolution spectroscopy of biologically relevant molecules

AC Stark Effect Observed in a Microwave–Millimeter/Submillimeter Wave Double-Resonance Experiment

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