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.

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.

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.

Fermi-Resonance Minima in the Vibrational Spectrum of Water in Crystalline Hydrates

1975 ◽  
Vol 53 (24) ◽  
pp. 3837-3840 ◽  
Author(s):  
David A. Othen ◽  
Osvald Knop ◽  
Michael Falk
Keyword(s):  
Low Temperature ◽  
Vibrational Spectrum ◽  
Infrared Absorption ◽  
Narrow Band ◽  
Fermi Resonance ◽  
Condensed Phases ◽  
Spectral Features ◽  
Bending Vibration ◽  
Absorption Features ◽  
Crystalline Hydrates

The infrared absorption and Raman spectra of polycrystalline tetrachlorocuprate(II) dihydrates M2CuCl4.2H2O (M = K, Rb, Cs, NH4) contain minima in the OH stretching region which sharpen at low temperature. These minima are shown to be 'Evans holes', or negative absorption features, caused by Fermi resonance between the broad and intense H2O stretching fundamental V1 and a relatively narrow band due to the overtone of the H2O bending vibration 2V2. Our findings confirm that Fermi resonance can lead to unusual spectral features, which must be taken into account in the analysis of the stretching region of the spectra of H2O and D2O in condensed phases, as has been done by Scherer etal. for the spectrum of liquid water.

scholarly journals Surface-Enhanced Infrared Absorption of o-Nitroaniline on Nickel Nanoparticles Synthesized by Electrochemical Deposition

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Yufang Niu ◽  
Jie Yao ◽  
Keyu Wang
Keyword(s):  
Infrared Absorption ◽  
Indium Tin Oxide ◽  
Nickel Nanoparticles ◽  
Ph Value ◽  
Glass Plate ◽  
Nickel Sulfate ◽  
Nickel Chloride ◽  
Attenuated Total Reflection ◽  
Enhancement Effect ◽  
Surface Enhanced

Nickel nanoparticles were electrochemically deposited on indium-tin oxide (ITO) coated glass plate in a modified Watt’s electrolyte. The surface-enhanced infrared absorption (SEIRA) effect of the nanoparticles was evaluated by attenuated total reflection spectroscopy (ATR-FTIR) using o-nitroaniline as a probe molecule. Electrodeposition parameters such as deposition time, pH value, and the type of surfactants were investigated. The morphology and the microstructure of the deposits were characterized by the field emission scanning electron microscope (FESEM) and the atomic force microscope (AFM), respectively. The results indicate that the optimum parameters were potential of 1.3 V, time of 30 s, and pH of 8.92 in the solution of 0.3756 mol/L diethanolamine, 0.1 mol/L nickel sulfate, 0.01 mol/L nickel chloride, and 0.05 mol/L boric acid. The FESEM observation shows that the morphology of nickel nanoparticles with best enhancement effect is spherical and narrowly distributed particles with the average size of 50 nm. SEIRA enhancement factor is about 68.

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