Search results for "Overtone"
showing 10 items of 34 documents
A combined theoretical and experimental determination of the electronic spectrum of acetone
1996
A combined ab initio and experimental investigation has been performed of the main features of the electronic spectrum of acetone. Vertical transition energies have been calculated from the ground to the ny→π∗, π→π∗, σ→π∗, and the n=3 Rydberg states. In addition, the 1A1 energy surfaces have been studied as functions of the CO bond length. The 1A1 3p and 3d states were found to be heavily perturbed by the π→π∗ state. Resonant multiphoton ionization and polarization‐selected photoacoustic spectra of acetone have been measured and observed transitions were assigned on internal criteria. The calculated vertical transition energies to the ny→π∗ and all Rydberg states were found to be in agreeme…
Hyperfine transitions in the first overtone mode of hydrogen deuteride
2020
Beyond the metrology and computational challenges associated with molecular hydrogen, key data are expected to assess the physics of simple molecular systems, and even the new physics beyond the standard model. To assist the deciphering of Doppler-free spectra obtained at very high accuracy ($\ensuremath{\sim}{10}^{\ensuremath{-}9})$, we report on hyperfine transitions of HD in the lowest vibrational levels of the ground electronic state. Using the spin-rotation, nuclear spin-spin, and quadrupolar hyperfine couplings determined by means of high-level quantum-chemical calculations, the hyperfine energy levels and the associated line intensity have been obtained by using tensorial momentum al…
Earlier timbre processing of instrumental tones compared to equally complex spectrally rotated sounds as revealed by the mismatch negativity.
2014
Harmonically rich sounds have been shown to be processed more efficiently by the human brain compared to single sinusoidal tones. To control for stimulus complexity as a potentially confounding factor, tones and equally complex spectrally rotated sounds, have been used in the present study to investigate the role of the overtone series in sensory auditory processing in non-musicians. Timbre differences in instrumental tones with equal pitch elicited a MMN which was earlier compared to that elicited by the spectrally rotated sounds, indicating that harmonically rich tones are processed faster compared to non-musical sounds without an overtone series, even when pitch is not the relevant infor…
Dynamic Fast Imaging Employing Steady State Acquisition Magnetic Resonance Imaging of the Vocal Tract in One Overtone Male Singer: Our Preliminary Ex…
2022
Summary Aims To demonstrate physiological changing of vocal tract's structures during overtone singing with commercial magnetic resonance imaging (MRI) Fast Imaging Employing Steady State Acquisition (FIESTA) dynamic sequence. Methods and Materials A 1.5 T MRI with a 16 channel head-and-neck coil and a FIESTA sequence were used. A temporal resolution of 0.155 sec (7 image/s). A single professional singer was studied. The MR acquisition is made while the singer performed a predetermined singing sequence. Three different overtone singing techniques were examined (L-technique, J-technique, and NG technique) and one effect (Ezengileer) applied to L-technique. For each overtone technique we eval…
Rotational Isomerism in Acetic Acid: The First Experimental Observation of the High-Energy Conformer
2003
The high-energy conformer of acetic acid (cis-AA) is produced in an Ar matrix by vibrational excitation of the OH stretching overtone of the ground conformational state (trans-AA). IR-absorption spectroscopy provides a clear identification of the reaction product. cis-AA converts back to trans-AA in a time scale of minutes at 8 K by tunneling. http://dx.doi.org/10.1021/ja038341a
Raman spectroscopy of acetic acid monomer and dimers isolated in solid argon
2011
Acetic acid (AA) monomer and its dimers were studied by means of Raman spectroscopy combined with the matrix isolation technique. All fundamental bands of CH3COOH monomer were identified, including the CH3 torsional mode. Additionally, three overtone or combination modes were observed as a result of their enhanced intensities by Fermi resonance (FR). Twenty bands of the cyclic dimer (C2h) were identified and assigned, among which appear all intermolecular modes. Bands due to two different higher energy forms of the dimer were also identified. The experimental assignments are supported by ab initio calculations. Copyright © 2011 John Wiley & Sons, Ltd.
High-Resolution Stimulated Raman Spectroscopy of Methane 13CD4 in the Pentad Region
1988
Abstract We present the first Raman spectrum of 13CD4 recorded at room temperature in the pentad region by inverse Raman spectroscopy, thus including the ν1 (A1), 2ν2 (A1), 2ν4 (A1), and ν2 + ν4(F1 + F2) Q branches. It is noteworthy that the overtone bands 2ν2 and 2ν4 are observed for the first time in a methane-like molecule by a coherent Raman process. The wide frequency range investigated, covering 45 cm−1 in three parts, contains more than 300 lines with uncertainty less than 10−3 cm−1 in most cases. These Raman data are combined with high-resolution infrared data in a weighted least-squares fit of the vibration-rotation constants of the pentad, thanks to a relevant partially reduced ef…
Enhancing the sound absorption of small-scale 3D printed acoustic metamaterials based on Helmholtz resonators
2018
Acoustic metamaterials have recently become of interest for their ability to attenuate sound by breaking the mass-density law. In this paper, acoustic metamaterials based on Helmholtz resonators and capable of attenuating sound up to 30 dB are fabricated for sound absorption applications in the small scale. The proposed metamaterials are subwavelength at a factor of $\lambda /12$ with respect to the lateral dimension of the units. The directional response due to the position of the acoustic source on the sound attenuation provided by the metamaterial is investigated by controlling the location of a loudspeaker with a robot arm. To enhance and broaden the absorption bands, structural modific…
Ab initio multi-reference perturbation theory calculations of the ground and low-lying electronic states of the KRb molecule
2016
The potential energy curves of the low-lying electronic states correlating up to the limit K(4p) + Rb(5s) of KRb molecule have been calculated using the multi-reference perturbation theory method at the CASSCF/ XMCQDPT2 level of theory without and with spin–orbit coupling. The calculated parameters of the ground X 1 R + state are in the best agreement among all previously performed ab initio calculations for the KRb molecule. The calculated vibrational intervals of the ground electronic term of the 39 K 85 Rb molecule describe the experiment with the accuracy within ±1 cm ?1 . The calculated intensities of the 2 1 R + (v 0 = 3, J 0 = 26) ? X 1 R + (v 00 = 0...24, J 00 = 25, 27) transitions …
The high overtone and combination levels of SF6 revisited at Doppler-limited resolution: A global effective rovibrational model for highly excited vi…
2017
Abstract Sulfur hexafluoride is an important prototypal molecule for modeling highly excited vibrational energy flow and multi quanta absorption processes in hexafluoride molecules of technological importance. It is also a strong greenhouse gas of anthropogenic origin. This heavy species, however, features many hot bands at room temperature (at which only 30% of the molecules lie in the ground vibrational state), especially those originating from the lowest, v 6 =1 vibrational state. Using a cryogenic long path cell with variable optical path length and temperatures regulated between 120 and 163 K, coupled to Synchrotron Radiation and a high resolution interferometer, Doppler-limited spectr…