scholarly journals Low-frequency (gigahertz to terahertz) depolarized Raman scattering off n-alkanes, cycloalkanes, and six-membered rings: a physical interpretation

2020 ◽  
Author(s):  
Andrew J. Farrell ◽  
Mario González Jiménez ◽  
Gopakumar Ramakrishnan ◽  
Klaas Wynne
Keyword(s):  
Kerr Effect ◽  
Ad Hoc ◽  
Low Frequency ◽  
Stress Tests ◽  
Frequency Spectra ◽  
Spectral Lineshape ◽  
Ultrafast Optical ◽  
Robust Model ◽  
Complex Liquids ◽  
Liquid Methane

Molecular liquids have long been known to undergo various distinct and simple intermolecular motions, from fast librations and cage rattling oscillations to slow orientational and translational diffusion. However, their resultant gigahertz to terahertz spectra are far from simple, appearing as broad shapeless bands that span many orders of magnitude of frequency making meaningful interpretation troublesome. <i>Ad hoc</i> spectral lineshape fitting has become a notoriously fine art in the field; a unified approach to handling such spectra is long overdue. Here we apply ultrafast optical Kerr-effect (OKE) spectroscopy to study the intermolecular dynamics of room temperature <i>n</i>-alkanes, cycloalkanes, and six-carbon rings, as well as liquid methane and propane. This work provides stress-tests and converges upon an experimentally robust model across simple molecular series and temperatures, providing a blueprint for the interpretation of the dynamics of van der Waals liquids. This will enable the interpretation of low frequency spectra of more complex liquids.

scholarly journals Low-frequency (gigahertz to terahertz) depolarized Raman scattering off n-alkanes, cycloalkanes, and six-membered rings: a physical interpretation

2020 ◽  
Author(s):  
Andrew J. Farrell ◽  
Mario González Jiménez ◽  
Gopakumar Ramakrishnan ◽  
Klaas Wynne
Keyword(s):  
Kerr Effect ◽  
Ad Hoc ◽  
Low Frequency ◽  
Stress Tests ◽  
Frequency Spectra ◽  
Spectral Lineshape ◽  
Ultrafast Optical ◽  
Robust Model ◽  
Complex Liquids ◽  
Liquid Methane

Molecular liquids have long been known to undergo various distinct and simple intermolecular motions, from fast librations and cage rattling oscillations to slow orientational and translational diffusion. However, their resultant gigahertz to terahertz spectra are far from simple, appearing as broad shapeless bands that span many orders of magnitude of frequency making meaningful interpretation troublesome. <i>Ad hoc</i> spectral lineshape fitting has become a notoriously fine art in the field; a unified approach to handling such spectra is long overdue. Here we apply ultrafast optical Kerr-effect (OKE) spectroscopy to study the intermolecular dynamics of room temperature <i>n</i>-alkanes, cycloalkanes, and six-carbon rings, as well as liquid methane and propane. This work provides stress-tests and converges upon an experimentally robust model across simple molecular series and temperatures, providing a blueprint for the interpretation of the dynamics of van der Waals liquids. This will enable the interpretation of low frequency spectra of more complex liquids.

Heart Rate Variability, Emotions, and Music

2010 ◽  
Vol 24 (2) ◽  
pp. 112-119 ◽  
Author(s):  
F. Riganello ◽  
A. Candelieri ◽  
M. Quintieri ◽  
G. Dolce
Keyword(s):  
Data Mining ◽  
Heart Rate ◽  
Heart Rate Variability ◽  
Vegetative State ◽  
Low Frequency ◽  
Emotional Reactions ◽  
Heart Beat ◽  
Healthy Controls ◽  
Frequency Spectra ◽  
Emotional Value

The purpose of the study was to identify significant changes in heart rate variability (an emerging descriptor of emotional conditions; HRV) concomitant to complex auditory stimuli with emotional value (music). In healthy controls, traumatic brain injured (TBI) patients, and subjects in the vegetative state (VS) the heart beat was continuously recorded while the subjects were passively listening to each of four music samples of different authorship. The heart rate (parametric and nonparametric) frequency spectra were computed and the spectra descriptors were processed by data-mining procedures. Data-mining sorted the nu_lf (normalized parameter unit of the spectrum low frequency range) as the significant descriptor by which the healthy controls, TBI patients, and VS subjects’ HRV responses to music could be clustered in classes matching those defined by the controls and TBI patients’ subjective reports. These findings promote the potential for HRV to reflect complex emotional stimuli and suggest that residual emotional reactions continue to occur in VS. HRV descriptors and data-mining appear applicable in brain function research in the absence of consciousness.

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