High-resolution photoelectron-spectroscopic investigation of the H2_2O+^+ cation in its A~+{\mathrm {\tilde A^+}} electronic state

The photoelectron spectrum of water has been recorded in the vicinity of the ${\mathrm {\tilde A^+}}$ $\leftarrow$ $\tilde{\mathrm{X}}$ transition between 112 000 and 116 000 cm$^{-1}$ (13.89-14.38 eV). The high-resolution allowed the observation of the rotational structure of several bands. Rotational assignments of the transitions involving the $\Pi(080)$, $\Sigma(070)$ and $\Pi(060)$ vibronic states of the $\tilde{\mathrm{A}}^+$ electronic state are deduced from previous studies of the $\tilde{\mathrm{A}}^+ - \tilde{\mathrm{X}}^+$ band system of H$_2$O$^+$ (Lew, Can. J. Phys. 54, 2028 (1976) and Huet et al., J. Chem. Phys. 107, 5645 (1997)) and photoionization selection rules. The transition to the $\Sigma(030)$ vibronic state is tentatively assigned.Comment: 10 pages, 4 figure

First observation of the N2O-OC van der waals complex and new set of experimental measurements on the N2O-CO complex.

Jet cooled infrared spectrum of the N$_2$O-CO van der Waals complex was observed in the region of the $\nu _1$ fundamental band of the N$_2$O monomer (2224 \wn) and in the CO stretch region (2143 \wn). These new measurements allowed the predicted less stable isomer, N$_2$O-OC, to be observed for the first time in both spectral regions. In addition, four combination bands were observed in the CO region. Two of these were assigned to N$_2$O-CO and the other two to N$_2$O-OC. Finally, a combination band in the N$_2$O region was assigned to the most stable isomer. In this talk I will discuss our results for the intermolecular vibrational frequencies and compare these to the recently published experimental values on similar systems CO$_2$-CO and CO$_2$-OC \footnote{S . Sheybani-Deloui, A. J. Barclay, K. H. Michaelian, A. R. W. McKellar, and N. Moazzen-Ahmadi, J. Chem. Phys 143, 121101 (2015).} and to ab initio predictions on this complex \footnote{M. Venayagamoorthy, T. A. Ford, THEOCHEM 717,111 (2005) }

Rotationally resolved photoelectron spectroscopic study of the Ã+ state of H2O+

This talk will present the analysis of the rotationally resolved pulsed-field-ionization zero-kinetic-energy (PFI-ZEKE) photoelectron spectrum of H$_2$O and will be focussed on the $\tilde{A}^+$$\leftarrow$$\tilde{X}$ transitions. H$_2$O$^+$ in the $\tilde{A}^+$ state is predicted to be linear \footnote{M. Brommer, B. Weis, B. Follmeg, P. Rosmus, S. Carter, N. C. Handy, H. J. Werner, and P. J. Knowles, J. Chem. Phys. 98, 5222 (1993)}. The sensitivity and the high resolution of PFI- ZEKE photoelectron spectroscopy allowed us to observe the rotational structure of low bending vibrational levels of the $\tilde{A}^+$ state of H$_2$O$^+$ from the $\tilde{X}$ ground electronic state of H$_2$O. The assignment of the rotational structure of ionic levels previously observed by optical spectroscopy of the $\tilde{A}^+$ - $\tilde{X}^+$ band system of H$_2$O$^+$ \footnote{T .Huet, I. H. Bachir, J. L. Destombes, and M. Vervloet, J. Chem. Phys. 107,5645 (1997).} \footnote{H. Lew, Can. J. Phys. 54, 2028 (1976).} will be presented and the intensity distribution of the photoelectron spectrum will be discussed in terms of the even or odd nature of the orbital angular momentum quantum number $l$ of the photoelectron. Tentative assignments will be presented for several low-lying vibrational levels of the $\tilde{A}^+$ state and compared with theoretical predictions $^c$. They will also be discussed in terms of the rotational structure of higher $\tilde{A}^+$ vibrational levels of the same symmetry

Investigation of acetylene-containing van der Waals complexes using high-level ab initio calculations and ultra-sensitive absorption experiments

Les complexes de van der Waals sont des entités constituées de différentes molécules liées par des interactions faibles (~kJ/mol). Ces agrégats présentent une réactivité particulière et jouent un rôle essentiel dans les phénomènes de solvatation et nucléation. Des moyens expérimentaux et théoriques pour étudier les complexes de van der Waals et en particulier ceux contenant de l’acétylène ont donc été développés dans ce travail. Nous avons utilisé et amélioré un montage expérimental appelé FANTASIO+ (Fourier trANsform, Tunable diode and quadrupole mAss spectrometers interfaced to a Supersonic expansIOn). Ce montage, composé d’un jet supersonique et d’un spectromètre à temps de déclin permet la production et la détection de ce genre de complexes. Le jet supersonique consiste en une détente adiabatique d’un gaz et assure par refroidissement à quelques Kelvins la production de complexes. La spectrométrie à temps de déclin mesure l’absorption d’un laser infra-rouge par ces molécules cibles assurant ainsi leur détection. Une diode laser nous a permis d’exciter deux fois l’étirement CH de l’acétylène. Nous avons pu détecter et analyser le spectre de vibration-rotation des complexes suivants :C2H2-Ne, C2H2-Ar, C2H2-Kr, C2H2-CO2, C2H2-N2O, et C2H2-C2H2. La molécule C2H2-CO2 et des isotopologues de C2H2-C2H2 ont également été étudiés à plus basse énergie durant un séjour à Calgary au Canada. Nos études ont démontré que ces complexes restaient liés à une énergie pouvant aller jusqu’à 130 fois l’énergie d’interaction entre les deux monomères. L’obtention de données à haute résolution spectrale permet également d’obtenir des données de références pour la validation de modèles théoriques et la planétologie. En particulier, la première détection de C2H2-Kr permettra peut-être une future observation de cet agrégat dans des atmosphères planétaires comme par exemple Titan. Pour avoir une approche globale de ces systèmes nous nous sommes tournés vers les outils de la chimie quantique pour caractériser l’interaction entre les entités du complexe. Des tests méthodologiques approfondis nous ont permis d’évaluer avec exactitude les surfaces d’énergie potentielle intermoléculaire des complexes contenant une molécule d’acétylène et un atome de krypton ou de xénon. van der Waals complexes are molecular systems in which the units or molecules are held together by weak interactions (~kJ/mol). These complexes present a peculiar reactivity and play a critical role in solvation and nucleation. Theoretical and experimental means were developed in this work to study such systems and in particular, complexes containing acetylene. In the context of this work the FANTASIO+ (Fourier trANsform, Tunable diode and quadrupole mAss spectrometers interfaced to a Supersonic expansIOn) experimental set-up was used and improved. This set-up, composed of a supersonic expansion and a cavity ring-down spectrometer, provides a way to produce and detect these complexes. The supersonic expansion is an adiabatic expansion which produces the complexes by cooling of the gas to few Kelvin. The CRDS set-up detect those complexes by infra-red laser absorption.Using laser diode to doubly excite the CH stretch of acetylene, one then succeeded to observe and analyze the ro-vibrational spectra of the following complexes: C2H2-Ne, C2H2-Ar, C2H2-Kr, C2H2-CO2, C2H2-N2O, et C2H2-C2H2. The C2H2-CO2 and isotopologues of C2H2-C2H2 were also studied at lower energy during a three months stay in Calgary, Canada. Our studies demonstrated that complexes stayed bound even at an energy 130 times higher than the energy holding the entities together. The high resolution data obtained during this work is also useful to validate theoretical models and planetology. The first detection of the C2H2-Kr complex, in particular, could allow its future detection in other atmospheres, i.e. on Titan.To have a global approach to these systems, the quantum chemistry tools were used to characterize the interaction between the partners of the complexes. Numerous methodological tests allowed us to accurately evaluate the intermolecular potential energy surfaces of the complexes containing an acetylene molecule and a krypton or a xenon atom.Doctorat en Sciencesinfo:eu-repo/semantics/nonPublishe

High resolution spectroscopic investigation of a new van der Waals complex: C2H2-Kr

The first observation in the near infrared of the 12C 2H2-Kr van der Waals complex is reported, leading to the determination of rotational constants and the prediction of the 1 0 1 (J′Ka′Kc′) ← 0 0 0 (J′′Ka′′Kc′′) microwave transition occurring at 3.334(4) MHz, useful for astrophysical detection.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

High resolution spectroscopy of the 2CH band in the 12C2H2-Ar van der Waals complex

info:eu-repo/semantics/publishe

Acetylene complexes relevant to Titan’s atmosphere: high resolution spectroscopy of C2H2-N2

info:eu-repo/semantics/nonPublishe

Observation of the linear C2H2-N2 van der Waals complex in the 2 CH range using CW-CRDS

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Infrared spectra of acetylene dimers and acetylene-nitrogen: (DCCD) 2, H-bonded DCCD-HCCH, and DCCD-NN in the 4.1 μm region

Infrared spectra of the weakly-bound T-shaped acetylene dimers DCCD-DCCD and DCCD-HCCH are studied in the region of the DCCD ν 3 fundamental (∼2440 cm -1) using a pulsed supersonic slit-jet expansion and a tunable diode laser probe. The K a = 0 ← 1 and 1 ← 0 subbands, corresponding to the vibration of the DCCD monomer at the "top" of the T, are analyzed. Compared to the analogous spectrum of HCCH-HCCH, the present results are much less perturbed. The tunneling splitting for (DCCD) 2 in the excited state is determined to be 141 MHz, a big reduction from the previously determined ground state value of 424 MHz. The dimer A rotational constants show a large apparent increase upon vibrational excitation, and we discuss whether this increase is real. The linear DCCD-NN complex is also observed as an impurity in the spectrum, and it too is found to be unperturbed, in contrast with HCCH-NN. © 2011 Elsevier Inc. All rights reserved