High-Resolution Continuous-Wave-Diode Laser Cavity Ring-Down Spectroscopy of the Hydrogen Fluoride Dimer in a Pulsed Slit Jet Expansion:  Two Components of the N = 2 Triad near 1.3 μm

Abstract

The near-infrared overtone spectra of the prototypical hydrogen-bond hydrogen fluoride dimer (HF)2 contain rich information on hydrogen bond dynamics. We report a study of the N=2 triad involving excitations with two quanta of HF stretching in (HF)2 around 1.3 microm (7500-7800 cm(-1)) by means of continuous-wave-diode laser cavity ring-down spectroscopy in a pulsed supersonic slit jet expansion. The analysis of the rotationally resolved overtone spectra allows the study of vibrational mode-selective kinetics, such as hydrogen bond predissociation with lifetimes tauPD and tunneling rearrangement (switching) processes with periods tausw obtained from the tunneling splitting DeltaT in highly excited vibrational states. The Ka=1<--0 transition of the Nj=22 band of (HF)2 has been reinvestigated by us in a supersonic jet expansion; the much improved data obtained here are in excellent agreement with several previous experimental results. Our analysis provides subband-level positions and properties 0(Ka=1(A+))=7711.37956(66) cm(-1), DeltaT=0.0936(10) cm(-1), and tauPD=1.3-1.9x10(-9) s, depending on the level symmetry A+ and B+. We have also analyzed spectra of the Nj=21 band, which we have observed for the first time in a supersonic jet with rotational resolution. For the Ka=0<--0 transition of this band, we find the band center at 0(A+)=7550.3555(26) cm(-1) and a tunneling splitting of DeltaT=0.0150(37) cm(-1). This level involves mostly excitation of the H-bonded HF stretching with two quanta. The mode-selective tunneling switching is in agreement with a simple picture of inhibited tunneling. These experimental values are close to those calculated on the "SO(-3)" potential energy hypersurface of Klopper, Quack, and Suhm. The N=2 triad also exhibits a strongly mode-selective predissociation dynamics, with a predissociation lifetime tauPD=4.99(84)x10(-11) s in the Nj=21 level, which is more than 20 times shorter than that for the Nj=22 level.

Experimental 2CH excitation in acetylene-containing van der Waals complexes

“…This field remained active [6][7][8][9][10][11], with recently renewed interest due to more stringent potential astrophysical and planetary relevance [12][13][14][15][16]. In the overtone vibrational range all previously highlighted challenges are magnified and therefore only few experimental studies were reported in the literature, such as of HF-Ar [17,18], (HF) 2 [19][20][21][22], (HCN) 2 [23], (H 2 O) 2 [24], (N 2 O) 2 [25], C 6 H 6 -Ar [26], OH-Ar [27], N 2 -HF [28], OC-HF [29] and H 2 -Ar [30]. Over recent years, the Brussels group has built an experimental set-up merging a powerful free supersonic jet and ultrasensitive high-resolution optical detection [31,32].…”

Molecular Quantum Mechanics and Molecular Spectra, Molecular Symmetry, and Interaction of Matter with Radiation

“…Sometimes, with very good data, the individual homogenous and inhomogeneous contributions can be separately evaluated (see for instance Hippler et al (2007) for an example).…”

Organic Chemistry - II

“…Under optimizedreaction conditions high conversion and good chemoand enantioselectivity werea chieved at reasonably lowc atalyst/substrate andm odifier/substrate ratios.I nterestingly,t he enantioselectivity of the homogeneous system with ( R )-BINAP as ligand depends strongly on the reaction temperature, whereas the opposite holds forthe heterogeneous system. -tricyclo (tc) DNA is at hirdg eneration antisense oligonucleotide that has been extensively studied in our lab [1].Werecently becameinterestedinthe pairing properties of the -anomeric form and observed parallelo rientation in the duplexes with natural DNA and RNAc omplements [2]. Interrestingly, within its own backbone series -tc-DNA exhibits poor thermal stability whichm akes it ac andidate for strand invasion applications.W ep resent recent results on thet riplex forminga nd strand invasionp ropertieso f -tcDNA.…”

“…Thec ombination of silver and organicm aterials is important because of supramolecular or surface aspectsa nd thef ormationo fn anostructures. Therei sagrowing interest in exploitingt heir optoelectronica nd chemical properties which have potential applications in nanoelectronics [1] ,b ioanalytical processes [2] and catalysis. [3] To gain insight into moleculari nteractions of silver ions with peptidesw e used ac ombinatoriala pproach.W es ynthesized twoe ncodeds plit-and-mix peptide librariesc ontaining the amino acids D/L -Asp, D/L -Ser, D/L -His, L -Tyr( AAn), linear spacersl ikeG ly,ß -Ala,a minohexanoica cida nd turn inducing motives like Pro-Gly,P ro-Aib and trans -2-aminocyclohexane carboxylic acid ( Xn).…”