Low-frequency infrared studies of trans-dihalotetraaminecobalt(III) complexes—a possible correlation of the energy of a skeletal vibrational mode with aquation rates

1975 ◽  
Vol 37 (4) ◽  
pp. 1049-1052 ◽  
Author(s):  
L.M. Eade ◽  
G.A. Rodley ◽  
D.A. House
Keyword(s):  
Vibrational Mode ◽  
Low Frequency ◽  
Infrared Studies

Static and Dynamic Structure of Molecular Monomers and Dimers of the Rare-earth Fluorides

2001 ◽  
Vol 56 (5) ◽  
pp. 381-385
Author(s):  
Z. Akdeniz ◽  
M . Gaune-Escard ◽  
M. P. Tosi
Keyword(s):  
Rare Earth ◽  
Bond Length ◽  
Geometrical Structure ◽  
Vibrational Mode ◽  
Dynamic Structure ◽  
Molecular Shape ◽  
Proposed Model ◽  
Infrared Studies ◽  
Charged Clusters ◽  
Good Agreement

Abstract We determine a model of the ionic interactions in RF3 compounds, where R is a rare-earth element in the series from La to Lu, by an analysis of data on the bond length and the vibrational mode frequencies of the PrF3, GdF3 and HoF3 molecular monomers. All RF3 monomers are predicted to have a pyramidal shape, displaying a progressive flattening of the molecular shape in parallel with the lanthanide contraction of the bond length. The vibrational frequencies of all monomers are calculated, the results being in good agreement with the data from infrared studies of matrix-isolated molecules. We also evaluate the geometrical structure and the vibrational spectrum of the La2F6 and Ce2F6 dimers, as a further test of the proposed model. -PACS 36.40.Wa (Charged clusters)

A Raman study of B203 through the liquid-glass transition range

1992 ◽  
Vol 02 ◽  
pp. C2-265-C2-270
Author(s):  
A. K. HASSAN ◽  
L. M. TORELL ◽  
L. BORJESSON
Keyword(s):  
Glass Transition ◽  
Correlation Length ◽  
Room Temperature ◽  
Vibrational Mode ◽  
Low Frequency ◽  
Boson Peak ◽  
Transition Range ◽  
Structural Correlation ◽  
Raman Study ◽  
Correlation Range

The low frequency Raman spectrum of B203 and the boroxol ring vibrational mode at 808 cm-1 have been studied from room temperature to 1273 K as the glass transforms to a melt. Both the low frequeney "boson" peak and the boroxol mode are markedly influenced by the glass transition. Raising the temperature above Tg the strength of the 808 cm-1 mode decreases linearly indicating the Similar behavior of the boroxol ring concentration. The boson peak shows a different temperature behavior, which mirrors that of the sound velo city. The structural correlation length demostrates the same correlation range in the liquid and the glass. The results, when compared with neutron diffraction measurements contradict a recently proposed relation between the "boson correlation length" and the position of the first sharp diffraction peak of the structure factor.

Donor-acceptor complexes formed by perfluoro-organo bromides and iodides with nitrogenous and other bases. II. Band shapes and widths in the absorption spectrum of gaseous CF3I-N(CH3)3

1971 ◽  
Vol 24 (12) ◽  
pp. 2493 ◽  
Author(s):  
A Mishra ◽  
ADE Pullin
Keyword(s):  
Vibrational Mode ◽  
Low Frequency ◽  
Molecular Complexes ◽  
Wave Number ◽  
Centrifugal Distortion ◽  
Band Shape ◽  
Gaseous Mixtures ◽  
Factors Affecting ◽  
Donor Acceptor ◽  
Vibration Rotation

The absorption band centred at c. 77 cm-1 in gaseous mixtures of CF3I and N(CH3)3 previously reported and attributed to the N-I stretching mode of the complex CF3I-N(CH3)3 has been carefully re-examined. This band is of interest as an example of a low frequency ?dissociative type? vibrational mode of a weak molecular complex. The band is asymmetric and apparently structureless with a half intensity width at room temperature of 28-30 cm-1. The width of the band may be accounted for as arising from transitions vi + vi+1 where vi is the vibrational quantum number of the N-I stretching mode with vi up to c. 10 making appreciable contribution to the intensity on the low wave-number side. Centrifugal distortion in the complex is considered. Centrifugal stretching and consequent weakening of the bond may shift the band envelope 2-3 cm-1 to lower wave numbers. Assessment of these and other factors affecting the band shape suggest that the fundamental frequency is probably c. 90 cm-1. The band shape of the vibrational mode of the complex at c. 272 cm-1 is briefly discussed. Many of the considerations presented in this paper should apply to vibration-rotation band shapes in other weak molecular complexes. Some general consequences of anharmonicity for the interpretation of the spectra of weak molecular complexes are discussed.

scholarly journals Excited State Frequencies of Chlorophyll f and Chlorophyll a and Evaluation of Displacement through Franck-Condon Progression Calculations

Molecules ◽  
2019 ◽  
Vol 24 (7) ◽  
pp. 1326 ◽  
Author(s):  
Noura Zamzam ◽  
Jasper van Thor
Keyword(s):  
Excited State ◽  
Chlorophyll A ◽  
High Frequency ◽  
Vibrational Mode ◽  
Low Frequency ◽  
State Frequency ◽  
B3lyp Calculations ◽  
Resonant Raman ◽  
Franck Condon ◽  
Chlorophyll F

We present ground and excited state frequency calculations of the recently discovered extremely red-shifted chlorophyll f. We discuss the experimentally available vibrational mode assignments of chlorophyll f and chlorophyll a which are characterised by particularly large downshifts of 131-keto mode in the excited state. The accuracy of excited state frequencies and their displacements are evaluated by the construction of Franck–Condon (FC) and Herzberg–Teller (HT) progressions at the CAM-B3LYP/6-31G(d) level. Results show that while CAM-B3LYP results are improved relative to B3LYP calculations, the displacements and downshifts of high-frequency modes are underestimated still, and that the progressions calculated for low temperature are dominated by low-frequency modes rather than fingerprint modes that are Resonant Raman active.

Past Results and Future Prospects of the Far-Infrared Studies of Hydrogen Bonding

1968 ◽  
Vol 22 (6) ◽  
pp. 641-649 ◽  
Author(s):  
R. J. Jakobsen ◽  
J. W. Brasch ◽  
Y. Mikawa
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonding ◽  
Hydrogen Bonds ◽  
Low Frequency ◽  
Far Infrared ◽  
Future Prospects ◽  
The Past ◽  
Ir Studies ◽  
Infrared Studies ◽  
Order Of Magnitude

In the past five years the number of papers concerned with far-ir studies of hydrogen bonding has increased by an order of magnitude. The results of some of these papers are presented in this review. Most of this work is concerned with the assignment of low frequency hydrogen bond vibrations. Since the major problem is reliable assignments, we discuss techniques used in making the assignments and emphasize the past work in which attempts have been made to substantiate those assignments. These assignments are discussed in terms of the different hydrogen bond vibrations associated with various types of hydrogen bonds. The main needs for future far ir hydrogen bond studies are listed.

scholarly journals PROBING INTERNAL STRESS AND CRYSTALLINITY IN WET FOAM VIA RAMAN SPECTROSCOPY

2009 ◽  
Vol 23 (19) ◽  
pp. 3913-3924
Author(s):  
T. K. BARIK ◽  
P. BANDYOPADHYAY ◽  
A. ROY
Keyword(s):  
Raman Spectroscopy ◽  
Internal Stress ◽  
Vibrational Mode ◽  
Low Frequency ◽  
Time Frame ◽  
Raman Shift ◽  
Specific Time ◽  
Time Intervals ◽  
Microscope Images ◽  
Average Size

In this paper, we correlate the internal stress and the characteristics of a vibrational mode in wet foam. Using microscope images, we estimate the average size of the bubbles in wet foam, at specific time intervals, over a duration of 24 h. Raman spectra are also recorded at the same time intervals, over the same time frame. We show that the internal stress, originated from the microscopic structural change of foam with aging, can be related to the observed Raman shift of the low-frequency methylene rocking mode of the constituent surfactant molecules in foam. In this paper, we also show the capability of the Raman spectroscopy to reveal the crystallinity in foamy materials, when studied for a longer period of time.

scholarly journals Ultrafast coherent oscillations reveal a reactive mode in the ring-opening reaction of fulgides

2015 ◽  
Vol 17 (21) ◽  
pp. 14045-14053 ◽  
Author(s):  
C. Slavov ◽  
N. Bellakbil ◽  
J. Wahl ◽  
K. Mayer ◽  
K. Rück-Braun ◽  
...  
Keyword(s):  
Ring Opening ◽  
Vibrational Mode ◽  
Low Frequency ◽  
Molecular Switches ◽  
Ring Opening Reaction ◽  
Coherent Dynamics ◽  
Reactive Mode

Ultrafast coherent dynamics reveals a low frequency vibrational mode governing the photochromic ring-opening reaction in indolylfulgide molecular switches.

NMR and low-frequency infrared studies of molecular motion in polymers

1969 ◽  
Vol 11 (11) ◽  
pp. 2848-2852 ◽  
Author(s):  
V.P. Roshchupkin ◽  
R.B. Lyubovskii ◽  
V.V. Kochervinskii ◽  
O.S. Roshchupkina
Keyword(s):  
Molecular Motion ◽  
Low Frequency ◽  
Infrared Studies
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