The rotational spectrum of epifluorohydrin measured by chirped-pulse Fourier transform microwave spectroscopy

Brown, Gordon G.; Dian, Brian C.; Douglass, Kevin O.; Geyer, Scott M.; Pate, Brooks H.

doi:10.1016/j.jms.2006.05.003

Cited by 118 publications

(58 citation statements)

References 34 publications

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“…[29] Briefly, a radiofrequency (rf) chirped pulse (0.2-1 GHz, 4 ms) generated by an arbitrary waveform generator (Tektronix AWG 710B) is mixed with the output of a MW synthesizer to produce a 2 GHz MW chirp in the 8-18 GHz range. This chirped pulse is amplified with a 20 W solid-state MW amplifier (MW Power, L0818-43) and then propagated into free space by using a wideband, high-gain, MW horn antenna (rf/MW Instrumentation, ATH7G18).…”

Section: Methodsmentioning

confidence: 99%

Perfluorobutyric Acid and Its Monohydrate: A Chirped Pulse and Cavity Based Fourier Transform Microwave Spectroscopic Study

Thomas

Serrato²,

Lin³

et al. 2014

Chemistry A European J

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Rotational spectra of perfluorobutyric acid (PFBA) and its monohydrate were studied with a broadband chirped pulse and a narrow-band cavity based Fourier transform microwave spectrometer, and high-level ab initio calculations. Extensive conformational searches were performed for both the acid and its monohydrate at the MP2/6-311++G(2d,p) level of theory. Two and three conformers were predicted to exist for PFBA and its monohydrate, respectively. One set of rotational transitions was observed and assigned for each, PFBA and its monohydrate. Based on the measured broadband spectra, we confidently conclude that only one dominant conformer exists in each case. The orientation of the hydroxyl group in PFBA was determined by using isotopic analysis. Comparison of the observed transition intensities and the calculated electric dipole moment components allowed us to identify the most stable monohydrate conformation, which takes on an insertion hydrogen-bonding topology. Comparisons to the shorter chain analogues, that is, trifluoroacetic acid, perfluoropropionic acid, and their monohydrates, are made to elucidate the general trend in their conformational preference and binding topologies.

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Section: Methodsmentioning

confidence: 99%

Perfluorobutyric Acid and Its Monohydrate: A Chirped Pulse and Cavity Based Fourier Transform Microwave Spectroscopic Study

Thomas

Serrato²,

Lin³

et al. 2014

Chemistry A European J

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“…The rotational spectrum of laser-populated vibrational states, shown in Fig. 2, was measured by using a recently developed broadband FTMW spectrometer (34).…”

Section: Methodsmentioning

confidence: 99%

Conformational isomerization kinetics of pent-1-en-4-yne with 3,330 cm ⁻¹ of internal energy measured by dynamic rotational spectroscopy

Dian

Brown

Douglass

et al. 2008

Proc. Natl. Acad. Sci. U.S.A.

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We demonstrate the application of molecular rotational spectroscopy to measure the conformation isomerization rate of vibrationally excited pent-1-en-4-yne (pentenyne). The rotational spectra of single quantum states of pentenyne are acquired by using a combination of IR-Fourier transform microwave double-resonance spectroscopy and high-resolution, single-photon IR spectroscopy. The quantum states probed in these experiments have energy eigenvalues of Ϸ3,330 cm ؊1 and lie above the barrier to conformational isomerization. At this energy, the presence of intramolecular vibrational energy redistribution (IVR) is indicated through the extensive local perturbations found in the high-resolution rotation-vibration spectrum of the acetylenic C-H stretch normalmode fundamental. The fact that the IVR process produces isomerization is deduced through a qualitatively different appearance of the excited-state rotational spectra compared with the pure rotational spectra of pentenyne. The rotational spectra of the vibrationally excited molecular eigenstates display coalescence between the characteristic rotational frequencies of the stable cis and skew conformations of the molecule. This coalescence is observed for quantum states prepared from laser excitation originating in the ground vibrational state of either of the two stable conformers. Experimental isomerization rates are extracted by using a threestate Bloch model of the dynamic rotational spectra that includes the effects of chemical exchange between the stable conformations. The time scale for the conformational isomerization rate of pentenyne at total energy of 3,330 cm ؊1 is Ϸ25 ps and is 50 times slower than the microcanonical isomerization rate predicted by the statistical Rice-Ramsperger-Kassel-Marcus theory.IVR ͉ microwave ͉ infrared ͉ double-resonance R otational spectroscopy is one of the most powerful tools in physical chemistry for the determination of gas-phase molecular structure (1). The development of molecular beam spectrometers for rotational spectroscopy-most notably the Fourier-transform microwave (FTMW) spectroscopy technique introduced by Balle and Flygare (2)-has greatly expanded the range of chemical systems that can be studied. Rotational spectroscopy can be routinely used to study challenging structural problems such as the conformations of large molecules (3), weakly bound molecular complexes (4), and radicals (5). In addition, rotational spectroscopy of low-energy vibrational and torsional levels can be used to determine accurate potential energy surfaces for large amplitude motion in ''floppy'' systems (1). Here we demonstrate a fundamentally unique application of rotational spectroscopy. We show that isomerization kinetics can be determined from the rotational spectrum of a highly vibrationally excited molecule.The physical basis of pure rotational spectroscopy is that when the total angular momentum is conserved, the rotational frequency is directly related to the principal moments of inertia of the molecule and, therefore, to its struct...

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“…Owing to the enormous advances in digital electronics, the situation has changed and one can now generate phase coherent broadband MW frequency ramps as well as digitize the molecular signal sufficiently fast, while simultaneously performing massive signal processing. The sensitivity and extreme broadband capabilities of the method are impressive (Brown et al 2006). The specifications of key components required for FP experiments are quite demanding.…”

Section: Fast-passage Free-space Ft-mw Instrumentsmentioning

confidence: 99%

Fourier Transform Microwave Spectroscopy Measurement and Instrumentation

Grabow

2011

Handbook of High‐resolution Spectroscopy

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Microwavemolecular spectroscopy is progressing impressively. In part, profiting from recent experimental developments that combine jet‐expansion sources with elaborate means for preparation of new chemical systems, advances in spectroscopic instrumentation — namely, the rise of very sensitive and high‐resolution time‐domain techniques — are even more significant. Precise structural studies have always been a strength of rotational spectroscopy; now problems arising from convoluted intramolecular dynamics, such as conformational, tautomeric equilibria, and other large amplitude motions, as well as intermolecular vibrational energy redistribution and isomerization, can be targeted with the unrivaled precision of rotational investigations. Numerous interesting chemical systems like molecules with multiple concurrent internal motions, larger complexes, aggregates, biomolecules, and transient species were characterized recently — positioning microwave spectroscopy today as a prime method for the investigation of multidimensional flexible systems. Rotational studies elucidate an extensive range of intermolecular interactions, ranging from hydrogen bonding and van der Waals interaction to the unusual effects observed in quantum solvation. The development of microwave pulsed excitation multiresonance techniques and the advent of instantaneous broadband‐coverage microwave spectroscopy are impressively boosting the capabilities of rotational spectroscopy to quite routinely disentangle the unique spectral signatures that encode the structure and dynamics of hitherto pathological molecular cases. The versatile capabilities of microwave coherence spectroscopy are outlined in the treatment of time‐dependent interaction of rotating molecules with radiation.

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The rotational spectrum of epifluorohydrin measured by chirped-pulse Fourier transform microwave spectroscopy

Cited by 118 publications

References 34 publications

Perfluorobutyric Acid and Its Monohydrate: A Chirped Pulse and Cavity Based Fourier Transform Microwave Spectroscopic Study

Perfluorobutyric Acid and Its Monohydrate: A Chirped Pulse and Cavity Based Fourier Transform Microwave Spectroscopic Study

Conformational isomerization kinetics of pent-1-en-4-yne with 3,330 cm ⁻¹ of internal energy measured by dynamic rotational spectroscopy

Fourier Transform Microwave Spectroscopy Measurement and Instrumentation

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The rotational spectrum of epifluorohydrin measured by chirped-pulse Fourier transform microwave spectroscopy

Cited by 118 publications

References 34 publications

Perfluorobutyric Acid and Its Monohydrate: A Chirped Pulse and Cavity Based Fourier Transform Microwave Spectroscopic Study

Perfluorobutyric Acid and Its Monohydrate: A Chirped Pulse and Cavity Based Fourier Transform Microwave Spectroscopic Study

Conformational isomerization kinetics of pent-1-en-4-yne with 3,330 cm −1 of internal energy measured by dynamic rotational spectroscopy

Fourier Transform Microwave Spectroscopy Measurement and Instrumentation

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Conformational isomerization kinetics of pent-1-en-4-yne with 3,330 cm ⁻¹ of internal energy measured by dynamic rotational spectroscopy