Publications de Thomas Rizzo | EPFL Graph Search

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We use infrared-visible double-resonance overtone excitation to prepare HOCl molecules in single, well-characterized rotational levels of the high OH stretching states v(OH) = 7 and v(OH) = 8. This work extends our recent studies on HOCl dissociation dynamics to higher energies above the dissociation threshold on the ground potential energy surface. In spite of a rapid increase of the vibrational coupling with v(OH), unimolecular dissociation is still limited by the rate at which energy initially deposited

We obtained gas-phase UV and IR spectra of 1:2 potassium ion-crown ether (CE) complexes (benzo-15-crown-5 (B15C5), benzo-18-crown-6 (B18C6), dibenzo-18-crown-6 (DB18C6), and 18-crown-6 (18C6)) at approximately 10 K and determined the structure and intermol ...

A method, system, and computer-readable medium for identifying and creating a database of isomers and isobars of molecules including the steps of performing isomer or isobar separation on molecules to obtain separate isomeric or isobaric molecules, measuri ...

Studying solvation of a large molecule on an atomic level is challenging because of the transient character and inhomogeneity of hydrogen bonding in liquid water. We studied water clusters of a protonated macrocyclic decapeptide, gramicidin S, which were p ...

The infrared predissociation spectrum of t-butyl hydroperoxide excited to the 4-nu-OH level reveals extensive mixing between the zeroth-order OH stretch state and nearly isoenergetic zeroth-order dark states. Because most of these dark states have an OH stretch quantum number of zero, the predissociation spectrum strongly resembles the infrared spectrum of an unexcited molecule. The observed intensity distribution in the predissociation spectrum is what one would expect if the eigenstates prepared by 4-nu-O

The structural characterization of glycans by mass spectrometry is particularly challenging. This is because of the high degree of isomerism in which glycans of the same mass can differ in their stereochemistry, attachment points, and degree of branching. ...

We describe a microwave-optical double resonance experiment designed for Stark effect measurements on molecules in excited vibrational energy levels of ground electronic states. This technique, which employs pulsed laser excitation and laser induced fluorescence detection, has been used to measure electric dipole moments in the 1(1), 5(1), and 5(2) vibrational states of formaldehyde. In addition, a Stark induced quantum beat experiment is briefly described. (C) 2003 American Institute of Physics.

Sequential pumping of the local OH stretch vibrations in hydrogen peroxide using infrared-optical double resonance permits spectroscopic access to the 4-nu(OH) + nu(OH)' combination level. Analysis of the rotationally resolved vibrational overtone spectra generated by this technique determines approximate rotational constants for this level and a value of 17 051.8 +/- 3.4 cm-1 for the O-O bond dissociation energy. The linewidths of individual zeroth-order rotational transitions increase sharply with increas

Determining the primary structure of glycans remains challenging due to their isomeric complexity. While high-resolution ion mobility spectrometry (IMS) has recently allowed distinguishing between many glycan isomers, the arrival-time distributions (ATDs) ...

We present here the design of a new tandem mass spectrometer that combines an electrospray ion source with a cryogenically cooled ion trap for spectroscopic studies of cold, gas-phase ions. The ability to generate large ions in the gas phase without fragme ...

We benchmark the performance of various computational approaches, ranging from the classical nonpolarizable force fields AMBER FF96 and FF99SB, the polarizable force fields AMBER FF02polEP and AMOEBAbio09 to the semiempirical DFT method SCC-DFTB. The test ...

We have measured an upper limit of 17 J/cm(2) for the threshold fluence for collision-fret CO2 laser IRMPD of silane by detecting the SiH2 product in its electronic and vibrational ground state. The threshold drops to similar to4 J/cm(2) when silane molecules are irradiated by all lines from a pulsed NH3 laser. This value further drops to less than 2 J/cm(2) when the molecules are pre-excited to the first Si-H stretch overtone. Using the NH3 laser on the 868 cm(-1) line, the dissociation yield of pre-excite

Our investigation of the phenylalanine/serine (Phe/Ser) protonated dimer suggests that the intermolecular interaction between the two amino acids is more complex than could have been anticipated from previous studies of similar systems. Isomer-specific inf ...

A method for a structural characterization of polysaccharides, comprising steps of characterizing a polysaccharide by physical measurements comprising a determination of a mass of the polysaccharide by means of mass spectrometry, a further determination of ...

Triple-resonance vibrational spectroscopy is used to determine the lowest dissociation energy, D0, for the water isotopologue HD16O as 41 239.7 ± 0.2 cm−1 and to improve D0 for H216O to 41 145.92 ± 0.12 cm−1. Ab initio calculations including systematic bas ...

Glycans covalently attached to protein biotherapeutics have a significant impact on their biological activity, clearance, and safety. As a result, glycosylation is categorized as a critical quality attribute that needs an adequate analytical approach to gu ...

This article presents recent work investigating the unimolecular dissociation rates of quantum state-selected molecules. Such studies provide the most stringent test for quantitative models of unimolecular reactions and their assumptions. After briefly reviewing the various experimental and theoretical techniques for state-resolved unimolecular dissociation rates, we present results obtained in our laboratory using the method of double resonance overtone photofragment spectroscopy. We focus on the unimolecu

Calculated structures of the two most stable conformers of a protonated decapeptide gramicidin S in the gas phase have been validated by comparing the vibrational spectra, calculat- ed from first- principles and measured in a wide spectral range using infr ...

Previous state-selected spectra of methanol in the 5ν1 OH stretch overtone region [O. V. Boyarkin, T. R. Rizzo, and D. S. Perry, J. Chem. Phys. 110 (23), 11346 (1999)] revealed structure indicating intramolecular vibrational redistribution (IVR) on three t ...

We present the spectroscopy and photofragmentation dynamics of two isomeric protonated dipeptides, H+AlaTyr and H+TyrAla, in a cold ion trap. By a combination of infrared-ultraviolet double resonance experiments and density functional theory calculations, ...

Thomas Rizzo

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Eigenstate-resolved unimolecular dissociation dynamics of HOCl at v(OH)=7 and 8

Structure and Interactions in 1:2 K+–Crown Ether Complexes via Gas-Phase Cold UV and IR Spectroscopy

A method and system to build an ir fingerprint database for the structural identification of biomolecules

Interplay of Intra- and Intermolecular H-Bonding in a Progressively Solvated Macrocyclic Peptide

Infrared spectrum of t‐butyl hydroperoxide excited to the 4νOH vibrational overtone level

Cryogenic Vibrational Spectroscopy Provides Unique Fingerprints for Glycan Identification

Fluorescence detected microwave Stark effect measurements in excited vibrational states of H2CO

Vibrational overtone spectroscopy of the 4νOH+νOH’ combination level of HOOH via sequential local mode–local mode excitation

A New Strategy Coupling Ion-Mobility-Selective CID and Cryogenic IR Spectroscopy to Identify Glycan Anomers

A new tandem mass spectrometer for photofragment spectroscopy of cold, gas-phase molecular ions

Assessing the performance of computational methods for the prediction of the ground state structure of a cyclic decapeptide

Collision-free infrared multiphoton dissociation of silane

Multiple Isomers and Protonation Sites of the Phenylalanine/Serine Dimer

A method for characterizing polysaccharides

Accurate bond dissociation energy of water determined by triple-resonance vibrational spectroscopy and ab initio calculations

Analyzing glycans cleaved from a biotherapeutic protein using ultrahigh-resolution ion mobility spectrometry together with cryogenic ion spectroscopy

State-to-state unimolecular reaction dynamics of highly vibrationally excited molecules

Conformational Structures of a Decapeptide Validated by First Principles Calculations and Cold Ion Spectroscopy

Conformational dependence of intramolecular vibrational redistribution in methanol

Conformation-specific infrared and ultraviolet spectroscopy of tyrosine-based protonated dipeptides