Publications de Thomas Rizzo | EPFL Graph Search

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The intensity of water absorption in the region of the solar spectrum plays a dominant role in atmospheric energy balance and hence strongly influences climate. Significant controversy exists over how to model this absorption accurately. We report dipole moment measurements of highly vibrationally excited water, which provide stringent tests of intensities determined by other means. Our measurements and accompanying calculations suggest that the best currently available potential and dipole surfaces do not

Vibrational overtone excitation of jet-cooled methanol, in combination with infrared laser assisted photofragment spectroscopy (IRLAPS) detection, reveals OH stretch bands that are significantly simplified with respect to room-temperature spectra. The simplification afforded by jet-cooling permits the observation of spectral splitting on the order of 50 cm(-1) in the region of the 5 nu(1) OH stretch overtone band. Tracking this splitting as a function of OH stretch vibrational level in combination with isot

We report quantitative dissociation yields for the reaction CH3OH (v(OH))-->nhnu CH3+OH induced by infrared multiphoton excitation of methanol pre-excited to various levels of the OH stretching vibration (v(OH)=0, 1, 3, 5). The yields are measured by detecting OH using laser induced fluorescence. It is demonstrated that for low levels of pre-excitation (v(OH)=0, 1, 3) there is a substantial nonlinear intensity dependence, as a higher yield is found for self mode-locked CO2 laser pulses (with higher peak int

The state-resolved reactivity of CH4 in its totally symmetric C-H stretch vibration (nu(1)) has been measured on a Ni(100) surface. Methane molecules were accelerated to kinetic energies of 49 and 63.5 kJ/mol in a molecular beam and vibrationally excited t ...

The isomeric heterogeneity of glycans poses a great challenge for their analysis. While combining ion mobility spectrometry (IMS) with tandem mass spectrometry is a powerful means for identifying and characterizing glycans, it has difficulty distinguishing ...

Infrared predissociation spectroscopy of nitric acid subsequent to vibrational overtone excitation reveals vibrational state mixing of the highly excited levels and probes the character of the coupled dark states. A visible dye laser excites the 4

Infrared-optical double resonance excitation of hydrogen peroxide using the v3 + v5 and V2 + v5 combination bands as intermediate levels prepares reactant molecules in single rotational states near the OO dissociation threshold. The band origins of the DELTA-upsilon-OH = 4 vibrational overtone transitions originating from these combination bands provide information on the anharmonicities between the OH stretch and the OO stretch and OOH bend, respectively. At low resolution the vibrational overtone transiti

Linewidths, unimolecular dissociation rates and product state distributions (PSDs) have been measured for single rovibratational states of the nu(1)=5-7 levels of gas-phase trans-nitrous acid (HONO) by double-resonance overtone photofragment spectroscopy (DROPS). The linewidth measurements, together with the unimolecular dissociation rates in 5nu(1), suggest that the intramolecular dynamics are not statistical but rather depend sensitively upon specific intramolecular couplings and the vibrational character

The analysis of carbohydrates, or glycans, is challenging for established structure-sensitive gas-phase methods. The multitude of possible stereo-, regio- and structural isomers make them substantially more complex to ana-lyze than DNA or proteins, and no ...

Using the technique of double-resonance overtone photofragment spectroscopy (DROPS), we have measured rotationally resolved vibrational overtone transitions to the previously unobserved 5v(1), 6v(1), and 7v(1) levels of gas-phase trans-nitrous acid (HONO) in its electronic ground state. Observing the onset of dissociation from different rovibrational states of 5v(1) near threshold determines the HO-NO bond energy to be D-0=16 772 +/- 14 cm(-1). Observed spectral splittings and broadening of individual rovib

We have measured electronic and conformer-specific vibrational spectra of hydrated dibenzo-18-crown-6 (DB18C6) complexes with potassium ion, K+center dot DB18C6 center dot(H2O)(n) (n = 1-5), in a cold, 22-pole ion trap. We also present for comparison spect ...

High-resolution ion mobility spectrometry (IMS) coupled with cryogenic infrared spectroscopy has proven to be a powerful technique for the identification of oligosaccharides. However, the need for an extensive database, combined with the scarcity of pure s ...

We have studied infrared multiphoton dissociation of CF3H pre-excited to the second C-H stretch overtone under collisional conditions in view of developing a laser isotope separation scheme for carbon-13. This single stage process results in a C2F4 product that has been enriched in carbon-13 to a level as high as 99% starting from a naturally abundant sample, implying an isotopic selectivity in excess of 9000. While most of the selectivity is gained at the pre-excitation step, it can be increased up to a fa

We report here measurements of rovibrational levels in the electronic ground state of water at the previously inaccessible energies above 26,000 cm-1. The use of laser double-resonance overtone excitation extends this limit to 34,200 cm-1, which correspond ...

We present evidence that following near-UV excitation, protonated tyrosine- or phenylalanine–containing peptides undergo intersystem crossing to produce a triplet species. This pathway competes with direct dissociation from the excited electronic state and ...

A method for analyzing a plurality of molecules with cryogenic vibrational spectroscopy including the steps of providing a packet of molecules in a ionized form, injecting the packet into an ion mobility section, spatially separating the ions of the packet ...

We use mass-resolved 2+2 resonantly enhanced multiphoton ionization (REMPD of silicon atoms to detect isotopically selective infrared multiphoton dissociation (IRMPD) of both ground-state and vibrationally pre-excited SiH4. To demonstrate that the detection scheme provides a faithful monitor of the isotopic composition of the primary dissociation products. this approach was first tested on the products generated by both IRMPD and UV photodissociation of phenylsilane. It was then employed to evaluate the deg

We present here ultraviolet and infrared spectra of protonated aromatic amino acids in a cold, 22-pole ion trap. Ultraviolet photofragmentation spectra of protonated tyrosine and phenylalanine show vibronically resolved bands corresponding to different sta ...

While the marriage of mass spectrometry and laser spectroscopy is not new, developments over the last few years in this relationship have opened up new horizons for the spectroscopic study of biological molecules. The combination of electrospray ionization ...

With a view toward laser isotope separation of Si, we have studied infrared multiphoton dissociation (IRMPD) of room temperature trichlorosilane, SiHCl3. Over the wavelength range investigated, multiphoton dissociation of the room temperature species exhibits a maximum efficiency at 12.6 mum and a threshold fluence of only similar to1 J/cm(2). Vibrational overtone preexcitation of SiHCl3 to the first SiH-stretch overtone (2nu(1)) prior to IRMPD results in a 10-fold increase of the dissociation yield compare

Thomas Rizzo

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Dipole moments of highly vibrationally excited water

Intramolecular energy transfer in highly vibrationally excited methanol .1. Ultrafast dynamics

Nonlinear intensity dependence in the infrared multiphoton excitation and dissociation of methanol pre-excited to different energies

State-resolved gas-surface reactivity of methane in the symmetric C-H stretch vibration on Ni(100)

Using SLIM-Based IMS-IMS Together with Cryogenic Infrared Spectroscopy for Glycan Analysis

INFRARED-SPECTROSCOPY OF VIBRATIONALLY EXCITED HONO2 - SHEDDING LIGHT ON THE DARK STATES OF INTRAMOLECULAR VIBRATIONAL-ENERGY REDISTRIBUTION

Unimolecular dissociation of hydrogen peroxide from single rovibrational states near threshold

Double-resonance overtone photofragment spectroscopy of trans-HONO. II. State- and time-resolved dissociation and OH-product state distributions

Separation and Identification of Glycan Anomers Using Ultrahigh-Resolution Ion Mobility Spectrometry and Cryogenic Ion Spectroscopy

Double-resonance overtone photofragment spectroscopy of trans-HONO. I. Spectroscopy and intramolecular dynamics

Microhydration Effects on the Encapsulation of Potassium Ion by Dibenzo-18-Crown-6

Identification of human milk oligosaccharide positional isomers by combining IMS-CID-IMS and cryogenic IR spectroscopy

Collisionally enhanced isotopic selectivity in multiphoton dissociation of vibrationally excited CF3H

Approaching the full set of energy levels of water

Fragmentation mechanism of UV-excited peptides in the gas phase

High-throughput cryogenic spectroscopy for glycan analysis

Isotopically selective infrared multiphoton dissociation of vibrationally excited SiH4

Conformation-specific spectroscopy and photodissociation of cold, protonated tyrosine and phenylalanine

Spectroscopic studies of cold, gas-phase biomolecular ions

Infrared laser chemistry of trichlorosilane in view of silicon isotope separation