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Sum-Frequency Generation Spectroscopy (sum-frequency + generation_spectroscopy)

Distribution by Scientific Domains
Chemistry100%

Selected Abstracts

Mechanistic Studies by Sum-Frequency Generation Spectroscopy: Hydrolysis of a Supported Phospholipid Bilayer by Phospholipase,A2,

ANGEWANDTE CHEMIE, Issue 13 2010
Yujin Tong
Die Strukturänderungen bei der durch das PLA2 -Enzym katalysierten Hydrolyse einer DPPC-Doppelschicht und der Mechanismus dieser Reaktion wurden auf molekularer Ebene für jede Schicht (rot und schwarz) der trägerfixierten Lipiddoppelschicht mithilfe von Summenfrequenzspektroskopie untersucht (DPPC=Dipalmitoylphosphatidylcholin). [source]

In Situ Characterization of Thermo-Responsive Poly(N -Isopropylacrylamide) Films with Sum-Frequency Generation Spectroscopy

CHEMPHYSCHEM, Issue 7 2010
Volker Kurz
Abstract The thermo-responsive behaviour of thiol modified poly(N -isopropylacrylamide) (pNIPAM) films immobilized on gold are probed by in situ broadband sum-frequency generation (SFG) spectroscopy. The pNIPAM films were prepared by atom transfer radical polymerization (ATRP) using a nitro-biphenyl-thiol (NBT)-SAM on a polycrystalline gold surface as a substrate. Additionally, Raman and infrared reflection absorption spectroscopy (IRRAS) are applied to spin-coated pNIPAM films. Molecular groups involved in the reorientation and disordering of the polymer chains during the LCST (lower critical solution temperature) transition of pNIPAM are identified. The characteristic vibrations of the CH3 groups show a gradual reorientation of the isopropyl groups within the pNIPAM film and instantaneous reorientation of the outermost CH3 groups around 32,°C. [source]

Identification of chemical species of fluorescein isothiocyanate isomer,I (FITC) monolayers on platinum by doubly resonant sum-frequency generation spectroscopy

JOURNAL OF RAMAN SPECTROSCOPY, Issue 11 2008
Toshiki Maeda
Abstract Doubly resonant sum-frequency generation (DR-SFG) spectroscopy of fluorescein-4-isothiocyanate isomer-I (FITC) monolayers on platinum was performed. Vibrational spectra of the monolayers for the IR wavenumber of 1750,1450 cm,1 were measured with visible probes ranging from 431 to 582 nm. Two vibrational bands at 1643 and 1610 cm,1 were observed, and their DR-SFG excitation profiles displayed different shapes. By rinsing the monolayers with an alkaline solution, the smaller wavenumber band disappeared and the larger wavenumber band gained intensity. On the basis of the spectral response to the rinsing, we concluded that the FITC molecules existed on platinum as deprotonated and protonated forms; the former corresponds to the 1643 cm,1 band and the latter to the 1610 cm,1 band. The deprotonated form was assigned to an anionic surface species, and the protonated form to a neutral surface species by comparing the DR-SFG excitation profiles with electronic absorption spectra of the protolytic forms of fluorescein in an aqueous solution (Sjöback R et al., Spectrochimica Acta A 1995; 51: L7,L21). The results demonstrate that the measurement of DR-SFG excitation profiles is a useful technique to identify chemical species of monolayers on metal surfaces. Copyright © 2008 John Wiley & Sons, Ltd. [source]

Time-resolved coherent Raman and sum-frequency generation spectroscopy with wavelength-tunable, short-pulse, photonic-crystal fiber light sources

JOURNAL OF RAMAN SPECTROSCOPY, Issue 8 2007
A. M. Zheltikov
Abstract Photonic-crystal fibers deliver frequency-tunable radiation within the wavelength range stretching from the ultraviolet to the near-infrared with output pulse widths from tens of femtoseconds to a few picoseconds and peak powers from a few watts to several megawatts, suggesting a convenient, efficient, and compact fiber format of short-pulse sources for time-resolved nonlinear spectroscopy and microscopy. Here, we examine the potential of photonic-crystal fiber light sources for time-resolved studies of ultrafast population and coherence relaxation dynamics in molecular systems using coherent anti-Stokes Raman scattering and two-photon-resonant sum-frequency generation. Copyright © 2007 John Wiley & Sons, Ltd. [source]