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The rovibrational energy levels (J = 0-3) and rotational spectra of seven isotopologues of the OCS-[(He).sub.2] complex have been determined by numerically exact basis set calculations. The interaction energy is represented as a sum of two-body terms consisting of the OCS-He potential, which Howson and Hutson (J. Chem. Phys. 2001, 115, 5059) obtained at the CCSD(T)/aug-cc-pVTZ level of theory, and the He-He potential that Jeziorska et al. (J. Chem. Phys. 2007, 127,124303) obtained with SAPT theory. Three-body effects and the quality of the potential are discussed. Comparison with experiment shows that microwave transitions can be predicted by this additive approach with an accuracy equal or better than 0.7% for all the observed spectral lines. A method for the three-dimensional representation of the helium density in the body-fixed frame is presented that highlights the highly delocalized nature of the helium subsystem. Key words: weakly bound clusters, quantum clusters, exact bound state calculations, microwave spectroscopy, rotational dynamics. Utilisant des ensembles de base numeriquement exacts, on a calcule les niveaux d'energie rovibrationnels (J = 0-3) et les spectres rotationnels de sept isotopologues du complexe OCS-[(He).sub.2]. L'energie d'interaction est represente par la somme de termes a deux corps formee du potentiel OCS-He que Howson et Hutson (J. Chem. Phys. 2001, 115, 5059)ont determine; au niveau CCSD(T)/aug-cc-pVTZ de la theorie et du potentiel He-He que Jeziorska et al. (J. Chem. Phys. 2007, 127, 124303) ont determine a l'aide de la theorie des perturbations adaptee pour la symetrie (TPAS). On discute aussi des effets de trois corps et de la qualite du potentiel. Une comparaison des resultats des calculs avec des resultats experimentaux montre que les transitions de microondes peuvent etre mieux predites par cette approche additive, avec une precision egale ou meilleure a 0,7 % pour toutes les raies spectrales observees. On presente une methode de representation tridimensionnelle de la densite de l'helium dans un squelette a corps fixes qui est caracterise par la nature hautement delocalisee du sous-systeme de l'helium. Mots-cles: agregats faiblement lies, agregats quantiques, calculs exacts de l'etat lie, spectroscopie de microondes, dynamique rotationnelle. [Traduit par la Redaction], Introduction Doped helium clusters offer a unique opportunity to understand quantum solvation and microscopic superfluidity, and this topic has been the subject of several studies in recent years. (1-13) Helium [...]

A pulsed, distributed feedback (DFB) quantum cascade (QC) laser centered at 970 [cm.sup.-1] was used in combination with an off-axis cavity enhanced absorption (CEA) spectroscopic technique for the detection of ammonia and ethylene. Here, the laser is coupled into a high-finesse cavity with an optical path length of ~76 m. The cavity is installed into a 53 cm long sample cell with a volume of 0.12 L. The laser is excited with short current pulses (5-10 ns), and the pulse amplitude is modulated with an external current ramp, resulting in a ~0.3 [cm.sup.-1] frequency scan. A demodulation approach followed by numerical filtering was utilized to improve the signal-to-noise ratio. We demonstrated detection limits of ~15 ppb and ~20 ppb for ammonia and ethylene, respectively, with less than 5 s averaging time. OCIS codes: 140.5965, 300.6340, 300.1030, 280.3420.

We demonstrate the application of a commercially available widely tunable continuous-wave external cavity quantum cascade laser as a spectroscopic source for the simultaneous detection of multiple gases. We measured broad absorption features of benzene and toluene between 1012 and 1063 [cm.sup.-1] (9.88 and 9.41 [micro]m) at atmospheric pressure using an astigmatic Herriott multipass cell. Our results show experimental detection limits of 0.26 and 0.41 ppm for benzene and toluene, respectively, with a 100 m path length for these two gases. [c] 2010 Optical Society of America OCIS codes: 140.5965, 280.0280, 300.6260, 300.6340.

Spectroscopic studies of OCS-doped [super 4]He clusters with 9-72 helium atoms were carried out along with rotational moment of inertia studies. It was found that the rotational constant, B, passes through a minimum at N=9 and then rises as the He atoms uncouple from the OCS rotational motion as a result of superfluid effects and broad unexpected oscillations in B were observed.

A high-resolution Fourier transform microwave spectroscopic investigation of the Xe-[([H.sub.2]O).sub.2] complex is presented. The analyses have suggested that an attractive electrostatic interaction as a result of induced dipole moments have made vital contributions to non-additive three-body effects.

Breath analysis can be a valuable, noninvasive tool for the clinical diagnosis of a number of pathological conditions. The detection of ammonia in exhaled breath is of particular interest for it has been linked to kidney malfunction and peptic ulcers. Pulsed cavity ringdown spectroscopy in the mid-IR region has developed into a sensitive analytical technique for trace gas analysis. A gas analyzer based on a pulsed mid-IR quantum cascade laser operating near 970 [cm.sup.-1] has been developed for the detection of ammonia levels in breath. We report a sensitivity of ~50 parts per billion with a 20 s time resolution for ammonia detection in breath with this system. The challenges and possible solutions for the quantification of ammonia in human breath by the described technique are discussed. OCIS codes: 300.6340, 170.4580, 280.3420, 140.5960, 300.1030.

Microwave and ab initio studies of the Xe-[H.sub.2]O van der Waals dimers are presented and the rotational transitions within two internal rotor states are measured using a Fourier transform microwave spectrometer. The obtained effective [H.sub.2]O orientations have supported the contribution to the wave functions in each state from the anti-hydrogen bonded orientations and nonplananr configurations and agreed with the structural parameters and force constants obtained from the rotational and centrifugal distortion constants.

Microwave rotational spectra of eleven isotopomers of the Ne3-NH3 van der Waals tetramer is measured with the help of a pulsed jet. The experimental findings are complemented by the construction of three ab initio potential energy surfaces for the Ne3-NH3 complex, each corresponding to a different internal geometry of NH3.

High-resolution infrared and microwave spectra of [He.sub.N]-carbonyl sulfide ([He.sub.N]-OCS) clusters with N ranging from 2 to 8 have been detected and unambiguously assigned. The spectra show the formation of a solvation layer beginning with an equatorial 'donut' of five helium atoms around the OCS molecule. The cluster moment of inertia increases as a function of N and overshoots the liquid droplet limit for N > 5, implying that even atoms in the first solvation shell are decoupled from the OCS rotation in helium nanodroplets. To the extent that this is due to superfluidity, the results directly explore the microscopic evolution of a phenomenon that is formally macroscopic in nature., One of the fundamental goals of cluster research is the interpretation of the properties of condensed phases in terms of those of their constituent atoms and molecules (1). However, the [...]

The Tn5432 erythromycin resistance (Emr) transposon was utilized for the isolation of Emr DNA fragments or cmr genes from Corynebacterium glutamicum mutant strains. The cmr gene of Corynebacterium glutamicum was composed of one open reading frame that encodes a 459-amino acid protein that conferred Emr in the mutant strain. Furthermore, the Cmr protein acted as a pump for the removal of different antibiotic compounds from the cytoplasm of the cell.

The reaction of Cr/Se multilayers, which involves interdiffusion of the single layers to an amorphous intermediate Cr-Se alloy and crystallization of Cr3Se4, is characterized using various techniques. The layers interdiffuse at around 300 degrees Celsius and the reaction yields a polycrystalline thin film of Cr3Se4 in a preferred orientation at a well-defined temperature.

Reports on the microwave and millimeter wave study of ortho-nitrogen states of carbon dioxide-nitrogen by pulsed molecular beam Fourier transform microwave spectrometer, a microwave-millimeter wave double resonance spectrometer and an OROTRON spectrometer. Nuclear quadropole hyperfine splittings due to the presence of two equivalent nitrogen nuclei.

Studies the Fourier transform microwave rotational spectra of ternary van der Waals complexes. Several experimental and theoretical studies on three-body nonadditive interactions in molecular systems; Observed spectra and analyses; Structural analyses.

Reports on the isotopic probing of very weak intermolecular forces between carbon dioxide and helium isotopomers. Microwave transition between the two lowest energy levels of the normal isotopomer of carbon dioxide-helium; Infrared measurements; Rotational transitions of five isotopes of carbon dioxide-helium.

Studies the van der Waals trimer NeArHCl with a pulsed molecular beam Fourier transform microwave spectrometer. Importance of the trimer for the understanding of correction terms proposed in investigations of nonadditive contributions in weakly bound molecular systems; Investigation of pure rotational spectra of four isotopomers.

Describes studies of the first rotational spectra of mixed noble gas trimers and tetrameres containing neon and argon atoms. Transitions of various isotopomers; Accurate values for rotational constants and centrifugal distortion constants; Determination and characterization of many-body nonadditive interactions; Signal strengths observed.

Measures rotation-tunneling spectra of the van der Waals complex Ne-cyclopropane and pure rotational spectra of Ar-cyclopropane and Kr-cyclopropane with a Fourier transform microwave spectrometer. Isotopomers observed; Rigidity of the complexes in the radial coordinate; Transition of isotopomers observed for complexes that contain monodeuterated cyclopropane.

The J = 1 - 0 transitions of the microwave spectra of H28Si35Cl, H28Si37Cl, H29Si35Cl, and H30Si35Cl were calculated at 14 - 15 GHz. The effective rotational constants obtained and the chlorine nuclear quadrupole link constants of the four isotopomers determined are presented.

Reports on the measurements of five pure rotational transitions of a mixed isotopomer of the CO-CO van der Waals dimer with a Fourier transform microwave spectrometer. Rotational transitions in the vibrational ground state; Isotopomeric variation of the sample composition; Comparison of measured frequencies with those predicted in recent infrared studies.

Rotational spectra of the Kr-H[sub 2]O van der Waals complex were measured in the frequency range 4-19 GHz using a pulsed jet cavity Fourier transform microwave spectrometer. The isotopomers studied include those of H[sub 2]O, HDO, D[sub 2]O, H[sub 2][sup 17]O and H[sub 2][sup 18]O with the six most abundant isotopes of Kr. A tunnelling splitting due to a large amplitude internal motion of the H[sub 2]O subunit that exchanges bonded and non-bonded hydrogen atoms was observed. Nuclear quadrupole hyperfine structure was resolved and measured for the complexes containing [sup 83]Kr, D, and [sup 17]O, and the corresponding nuclear quadrupole coupling constants were determined. These were used to estimate structural parameters and to derive information about the intermolecular dynamics. The results, and in some instances the spectroscopic constants themselves, were compared with experimental and theoretical data previously reported for Ar-H[sub 2]O. [ABSTRACT FROM AUTHOR]

Presents a double-resonance spectrometer for van der Waals complexes investigation. Schematic design of the instrument; Use of the Fourier transform microwave spectrometer and the phase stabilization system of the backward wave oscillator; Sensitivity and resolution capabilities of the technique.