Toward Detection of the Molecular Parity Violation in Chiral Ru(acac) and Os(acac).

We present a theory-experiment investigation of the helically chiral compounds Ru(acac) and Os(acac) as candidates for next-generation experiments for detection of molecular parity violation (PV) in vibrational spectra. We used relativistic density functional theory calculations to identify optimal vibrational modes with expected PV effects exceeding by up to 2 orders of magnitude the projected instrumental sensitivity of the ultrahigh resolution experiment under construction at the Laboratoire de Physique des Lasers in Paris. Preliminary measurements of the vibrational spectrum of Ru(acac) carried out as the first steps toward the planned experiment are presented.

Synchrotron-Based High Resolution Far-Infrared Spectroscopy of -Butadiene.

The high resolution far-infrared spectrum of -butadiene has been reinvestigated by Fourier-transform spectroscopy at two synchrotron radiation facilities, SOLEIL and the Canadian Light Source, at temperatures ranging from 50 to 340 K. Beyond the well-studied bands, two new fundamental bands lying below 1100 cm, ν and ν, have been assigned using a combination of cross-correlation (ASAP software) and Loomis-Wood type (LWWa software) diagrams. While the ν analysis was rather straightforward, ν exhibits obvious signs of a strong perturbation, presumably owing to interaction with the dark ν + ν state.

Nuclear Spin Symmetry Conservation in HO Investigated by Direct Absorption FTIR Spectroscopy of Water Vapor Cooled Down in Supersonic Expansion.

We report the results of an experimental study related to the relaxation of the nuclear spin isomers of the water molecule in a supersonic expansion. Rovibrational lines of both ortho and para spin isomers were recorded in the spectral range of HO stretching vibrations at around 3700 cm using FTIR direct absorption. Water vapor seeded in argon, helium, or oxygen or in a mixture of oxygen and argon was expanded into vacuum through a slit nozzle.

Competition between inter- and intra-molecular hydrogen bonding: An infrared spectroscopic study of jet-cooled amino-ethanol and its dimer.

The Fourier transform IR vibrational spectra of amino-ethanol (AE) and its dimer have been recorded at room temperature and under jet-cooled conditions over the far and mid infrared ranges (50-4000 cm) using the White-type cell and the supersonic jet of the Jet-AILES apparatus at the synchrotron facility SOLEIL. Assignment of the monomer experimental frequencies has been derived from anharmonic frequencies calculated at a hybrid CCSD(T)-F12/MP2 level. Various thermodynamical effects in the supersonic expansion conditions including molar dilution of AE and nature of carrier gas have been used to promote or not the formation of dimers.

Standard free energy of the equilibrium between the trans-monomer and the cyclic-dimer of acetic acid in the gas phase from infrared spectroscopy.

Survey jet-cooled spectra of acetic acid have been recorded in the infrared region (200-4000 cm(-1)) over a wide range of expansion conditions. From the variations of the relative intensities of the signals, vibrational transitions have been assigned unambiguously to the trans-monomer and cyclic-dimer. The IR-active fundamental frequencies have been determined at the instrumental accuracy of 0.

Structural and dynamic properties of a hydrogen bond from the study of the CH3Cl-HCl complex and isotopic species.

The microwave (4-20 GHz range) and infrared (HCl and DCl stretch ranges) spectra of six isotopic species of the CH3Cl-HCl hydrogen bond complex have been recorded for the first time and analyzed with the support of high level ab initio calculations (MP2 and CCSD(T) levels). Accurate molecular parameters, including rotational, quartic centrifugal distortion, and nuclear-quadrupole coupling constants, vibrational frequencies, and anharmonic coupling constants, are presented in this paper. These parameters have then been used to estimate the hydrogen bond geometry and confirm the strong coupling between intramolecular and low frequency intermolecular modes.

High resolution spectroscopy of methyltrioxorhenium: towards the observation of parity violation in chiral molecules.

Originating from the weak interaction, parity violation in chiral molecules has been considered as a possible origin of biohomochirality. We have proposed the observation of molecular parity violation using the two-photon Ramsey fringes technique on a supersonic beam. As a first step in this direction, a detailed spectroscopic study of methyltrioxorhenium (MTO) has been undertaken.

Progress toward the first observation of parity violation in chiral molecules by high-resolution laser spectroscopy.

Parity violation (PV) effects in chiral molecules have so far never been experimentally observed. To take up this challenge, a consortium of physicists, chemists, theoreticians, and spectroscopists has been established and aims at measuring PV energy differences between two enantiomers by using high-resolution laser spectroscopy. In this article, we present our common strategy to reach this goal, the progress accomplished in the diverse areas, and point out directions for future PV observations.

Fourier transform infrared spectroscopy and ab initio theory of acid-hydrogen sulfide clusters: H2S-HCl, D2S-DCl and H2S-(HCl)(2).

The rotationally resolved Fourier transform infrared (FTIR) spectrum of the nu(s) HCl and DCl stretching bands for the hydrogen bonded complex H2S-HCl and its isotopomer D2S-DCl have been observed in a supersonic jet at 0.02 cm(-1) resolution. In the same experimental conditions, two additional bands observed without rotational structure in the HCl range of the dimer have been assigned to the cyclic trimer H2S-(HCl)(2).

Vibrational dynamics of the hydrogen bond in H(2)S-HF: Fourier-transform-infrared spectra and ab initio theory.

The rotationally resolved infrared spectrum of the hydrogen bonded complex H(2)S-HF and of its isotopomer D(2)S-DF in the HF/DF stretching range have been observed in a supersonic jet Fourier-transform infrared (FTIR) experiment and indicate a predissociation lifetime of 130 ps for H(2)S-HF. Complementary spectra taken at a temperature of 190 K in a cell without resolved rotational structure indicate the presence of strong anharmonic couplings between low frequency intermolecular modes and the HF donor stretch mode previously observed in other complexes with heavier acceptor molecules without rotational fine structure. The anharmonic analysis of the hot band progressions and of the rotational data confirm the coupling mechanism.

Chlorofluoroiodomethane as a potential candidate for parity violation measurements.

CHFClI is among the more favorable molecules for parity violation (PV) measurements in molecules. Despite the fact that calculated PV effects are two orders of magnitude smaller than in some organometallic compounds, CHFClI displays interesting features which could make possible a new experimental PV test on this molecule. Indeed, ultrahigh resolution spectroscopy using an ultrastable CO(2) laser is favored by several intrinsic properties of this molecule.