scholarly journals IR-UV Double Resonance Spectrum of Acetylene Below and Above the Predissociation Threshold

1994 ◽  
Vol 14 (1-3) ◽  
pp. 161-182 ◽  
Author(s):  
Masaaki Fujii ◽  
Shigeki Tanabe ◽  
Yasuo Okuzawa ◽  
Mitsuo Ito
Keyword(s):  
Double Resonance ◽  
Supersonic Jet ◽  
Fermi Resonance ◽  
Resonance Spectroscopy ◽  
Fundamental Vibration ◽  
Vibrationally Excited ◽  
Bending Vibration ◽  
Acetylene Molecule ◽  
Stretching Vibration ◽  
The Difference

The Ã1Au ← X˜1∑g+ electronic transition of the vibrationally excited acetylene molecule was studied by IR–UV double resonance spectroscopy in gas and in a supersonic jet. The C–H antisymmetric stretching vibration νCHant in the à state was clearly observed when the molecule was excited to the νCHsym + νCHant combination vibration in the X˜ state by the IR laser. When the νCHant fundamental vibration was excited, the C–H in-plane cis-bending vibration νcis(in) in the à state was observed strongly, while νCHant almost disappeared. The difference was interpreted in terms of Fermi resonance of the νCHant fundamental vibration in X˜. The predissociation threshold was newly determined to be 46,439˼46,673 cm-1 (133.11 ± 0.33 kcal/mol). In the region above the predissociation threshold, strong vibrational mixing was found. The higher members of the progression of the trans-bending vibration starting from νCHant were assigned. It was suggested that the nonradiative relaxation accelerated in the region above 51,744 cm-1.

Conformational preferences of monohydrated clusters of imidazole derivatives revisited

2015 ◽  
Vol 17 (31) ◽  
pp. 20080-20092 ◽  
Author(s):  
Aditi Bhattacherjee ◽  
Sanjay Wategaonkar
Keyword(s):  
Double Resonance ◽  
Supersonic Jet ◽  
Resonance Spectroscopy ◽  
Imidazole Derivatives ◽  
Conformational Preferences ◽  
Double Resonance Spectroscopy

IR-UV double resonance spectroscopy was used to identify the conformers of monohydrated benzimidazole andN-methylbenzimidazole in a supersonic jet. A new OH–N bound conformer relevant to histidine containing proteins was discovered. The long standing differences in the literature about the relative energies and abundance of the monohydrated imidazole derivatives have also been resolved.

scholarly journals Surface-enhanced infrared absorption studies towards a new optical biosensor

2016 ◽  
Vol 7 ◽  
pp. 1736-1742 ◽  
Author(s):  
Lothar Leidner ◽  
Julia Stäb ◽  
Jennifer T Adam ◽  
Günter Gauglitz
Keyword(s):  
Infrared Absorption ◽  
Resonance Effect ◽  
Optical Biosensor ◽  
Fermi Resonance ◽  
Infrared Range ◽  
Bending Vibration ◽  
Thickness Change ◽  
Additional Information ◽  
Surface Enhanced ◽  
Stretching Vibration

Reflectometric interference spectroscopy (RIfS), which is well-established in the visual regime, measures the optical thickness change of a sensitive layer caused, e.g., by binding an analyte. When operated in the mid-infrared range the sensor provides additional information via weak absorption spectra (fingerprints). The originally poor spectra are magnified by surface-enhanced infrared absorption (SEIRA). This is demonstrated using the broad complex fluid water band at 3300 cm−1, which is caused by superposition of symmetric, antisymmetric stretching vibration, and the first overtone of the bending vibration under the influence of H-bonds and Fermi resonance effect. The results are compared with a similar experiment performed with an ATR (attenuated total reflectance) set-up.

Analysis of the Structures and Thermal Properties of Hexanediamine Adipate and Pentanediamine Adipate

2018 ◽  
Vol 876 ◽  
pp. 76-83
Author(s):  
Xiao Wan Yang ◽  
Xin Min Hao ◽  
Jian Ming Wang ◽  
Yan Bin Liu ◽  
Hong Liang Kang
Keyword(s):  
Thermal Properties ◽  
Melting Point ◽  
Infrared Spectra ◽  
Adipic Acid ◽  
Decomposition Temperature ◽  
Bending Vibration ◽  
Out Of Plane ◽  
Stretching Vibration ◽  
Acid Reaction ◽  
The Difference

Hexanediamine adipate, pentanediamine adipate and bio-based pentanediamine adipate were prepared by adipic acid reaction with 1,6-hexanediamine, 1,5-pentanediamine and bio-based 1,5-pentanediamine, respectively. Their structures and thermal properties have been analyzed by infrared spectra, SEM, DSC and TGA. Infrared spectra showed the main differences between 1,6-hexanediamine and 1,5-pentanediamine for the deformation vibration and out of plane bending vibration of N−H. Hexanediamine adipate and pentanediamine adipate had the difference at the asymmetric stretching vibration of −COO-−. The crystal morphologies of hexanediamine adipate and pentanediamine adipate showed dendritic and acicular, respectively. The melting point of pentanediamine adipate, pentanediamine adipate and bio-based pentanediamine adipate were 208.0 °C, 182.3 °C and 182.9 °C, respectively. The polymerization of hexanediamine adipate, pentanediamine adipate and bio-based pentanediamine adipate happened at 201.0, 190.2 and 194.9 °C, respectively. And the decomposition temperature of PA66, PA56 and bio-based PA56 were 401.8, 403.5 and 405.2 °C, respectively.

Fermi Resonance of Infrared Vibrations in the —NH2 Groups of Polynucleotides

1971 ◽  
Vol 49 (23) ◽  
pp. 3795-3798 ◽  
Author(s):  
G. Zundel ◽  
W. D. Lubos ◽  
K. Kölkenbeck
Keyword(s):  
Hydrogen Bonds ◽  
Harmonic Vibration ◽  
Fermi Resonance ◽  
Bending Vibration ◽  
Doublet Structure ◽  
Stretching Vibration ◽  
Stretching Vibrations ◽  
Band Pair ◽  
Hydrogen Bonded

The —NH2 group causes an intensive band pair in the i.r. spectra of DNA, r.RNA, poly (A + U), and poly (G + C). One band occurs at 3330, another at 3180 cm−1. This band pair is due to the NH stretching vibration of the hydrogen-bonded NH group as well as to the harmonic vibration of the —NH2 bending vibration, whereby these vibrations are coupled via Fermi resonance. This follows on comparison with papers on amines. The weak shoulder in the 3500–3400 cm−1 range is to be assigned to the stretching vibrations of the non hydrogen-bonded NH groups. The doublet structure disappears to a large extent in the denaturated DNA, since the strength of the Fermi resonance depends on the strength of the hydrogen bonds and the hydrogen bonds are of differing strength, due to the bending and stretching. The relative intensities of the two bands are interchanged in the corresponding band pair of the —ND2 groups, for which an explanation can also be given.

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