Experimental observation of the ν1+3ν3 combination bands of 16O14N18O and 18O14N18O in the near infrared spectral region.

The first observation of the ν1+3ν3 combination band of the nitrogen dioxide isotopologue 16O14N18O is presented. The band was measured using Fourier-Transform Incoherent Broad-Band Cavity Enhanced Absorption Spectroscopy (FT-IBBCEAS) in the region between 5870 cm-1 and 5940 cm-1. To confirm the assignment, the band was simulated using a standard asymmetric top Watson Hamiltonian using extrapolated rotational and centrifugal distortion constants. Furthermore, the first experimental observation of the ν1+3ν3 band of the 18O14N18O isotopologue is also reported. The positions of ro-vibrational lines of the ν1+3ν3 band of the naturally most abundant isotopologue 16O14N16O were used for wavenumber calibration of line positions.

[Initial ophthalmic manifestation of a fatal underlying disease : Importance of perimetry in unspecific visual deterioration]. / Ophthalmologische Erstmanifestation einer letalen Grunderkrankung : Stellenwert der Perimetrie bei unspezifischer Sehverschlechterung.

A 55-year-old male patient presented with bilateral blurred vision. Chronic lymphocytic leukemia was generally known in the medical history, which was treated by immunochemotherapy with fludarabine, cyclophosphamide and rituximab. Static perimetry revealed a homonymous hemianopia to the left. The neurological examination was otherwise unremarkable. Progressive multifocal leukoencephalopathy (PML) was diagnosed by cranial magnetic resonance imaging and detection of JC virus DNA in the cerebrospinal fluid. The PML is a rare demyelinating disease of the central nervous system caused by reactivation of the JC virus. It affects patients with HIV, malignant hematological diseases and immunomodulatory therapy. A specific, antiviral treatment does not yet exist. The prognosis of PML is therefore poor. After a progressive course of the disease the patient died 4 months after the diagnosis.

New laboratory intercomparison of the ozone absorption coefficients in the mid-infrared (10 µm) and ultraviolet (300-350 nm) spectral regions.

Knowing the ozone absorption cross sections in the ultraviolet and infrared spectral range, with an accuracy of better than 1%, is of the utmost importance for atmospheric remote-sensing applications. For this reason, various ozone intensity intercomparisons and measurements have been published these last years. However, the corresponding results proved not to be consistent and thus have raised a controversial discussion in the community of atmospheric remote-sensing. This study, where great care has been taken to avoid any possible error, reports a new laboratory intercomparison of the ozone absorption coefficients in the mid-infrared (10 µm) and ultraviolet (300-350 nm) spectral regions. It gives a new piece of information to the puzzling problem concerning the ozone IR and UV cross sections and confirms that the IR and UV cross sections recommended in the literature are in disagreement of about 4%.

High-resolution infrared spectroscopy of trans- and cis-H(18)ON(18)O: equilibrium structures of the nitrous acid isomers.

In this paper, we present the first high-resolution spectra and analysis of the nu 4 fundamental bands of fully (18)O-substituted nitrous acid, trans- and cis-H(18)ON(18)O. These bands are not perturbed by neighboring vibrational levels and were used to determine for the first time accurate rotational and centrifugal distortion constants of the ground and nu 4 = 1 states of trans- and cis-H(18)ON(18)O. The ground-state rotational constants were then used, together with the rotational constants of other HONO isotopic species and with rotation-vibration parameters from ab initio calculations, to determine accurate semi-experimental equilibrium structures of trans- and cis-HONO. Our study confirms the results of a recent work by Demaison et al. (J. Phys. Chem. A 2006, 110, 13609-13617) concerning the structure of trans-HONO, whereas the new structure of cis-HONO obtained in this paper is a significant improvement compared with the previous work of Cox et al. (J. Mol. Struct. 1994, 320, 91-106). The recommended parameters for the equilibrium structure of cis-HONO are r(e)(ON) = 1.1816(10) A, r(e)(N-O) = 1.3887(10) A, r(e)(O-H) = 0.9744(7) A, angle(e)(ONO) = 113.18(1) degrees, and angle(e)(HON) = 104.67(4) degrees.

Laboratory intercomparison of the ozone absorption coefficients in the mid-infrared (10 microm) and ultraviolet (300-350 nm) spectral regions.

For the measurement of atmospheric ozone concentrations, the mid-infrared and ultraviolet regions are both used by ground-, air-, or satellite-borne instruments. In this study we report the first laboratory intercomparison of the ozone absorption coefficients using simultaneous measurements in these spectral regions. The intercomparison shows good agreement (around 98.5%) between the HITRAN 2000 recommendation for the mid-infrared and the most reference measurements in the ultraviolet regions, whereas systematic differences of about 5.5% are observed when using the recommendation of HITRAN2003 for the mid-infrared. Possible reasons for this discrepancy are discussed. Future measurements are clearly needed to resolve this issue.

New High-Resolution Analysis of the nu(3) Band of the (15)N(16)O(2) Isotopomer of Nitrogen Dioxide by Fourier Transform Spectroscopy.

New high-resolution Fourier transform absorption spectra of an (15)N(16)O(2) isotopic sample of nitrogen dioxide were recorded at the University of Bremen in the 6.3-µm region. Starting from the results of a previous study [Y. Hamada, J. Mol. Struct. 242, 367-377 (1991)], a new and more extended analysis of the nu(3) band located at 1582.1039 cm(-1) has been performed. The spin-rotation energy levels were satisfactorily reproduced using a theoretical model which takes into account both the Coriolis interactions between the spin-rotation energy levels of the (001) vibrational state with those of the (020) and (100) states and the spin-rotation resonances within each of the NO(2) vibrational states. Precise vibrational energies and rotational, spin-rotation, and coupling constants were obtained in this way for the first triad of (15)N(16)O(2) interacting states {(020), (100), (001)}. Finally, a comprehensive list of line positions and line intensities of the {nu(1), 2nu(2), nu(3)} interacting bands of (15)N(16)O(2) was generated, using for the line intensities the transition moment operators which were obtained previously for the main isotopic species. Copyright 2000 Academic Press.

The Far Infrared Spectrum of HOCl: Line Positions and Intensities.

The far infrared spectrum of HOCl has been recorded at high resolution between 20 and 360 cm-1 by means of Fourier transform spectroscopy, and it was possible to observe pure rotation lines involving rotational levels with high Ka quantum numbers (up to Ka = 9). These lines combined with microwave and tunable far infrared data available in the literature were least squares fitted using a Watson-type Hamiltonian. The fitting leads to precise sets of rotational and centrifugal distortion constants for the ground states of both isotopomers HO35Cl and HO37Cl. Also relative line intensities were measured and their fitting allowed the determination of rotational corrections to the b-component of the permanent transition moment. Finally, to get Hamiltonian constants consistent with the newly determined ground state constants for the (100), (010), (001) vibrational states, available data concerning the nu1, nu2, and nu3 bands were refitted. Three interesting points are to be stressed. For the (001) state, we were able to complete the existing data with rotation lines observed in our spectra up to rather high Ka values (Ka = 7). For HO35Cl, we were able to show that some (010) and (100) levels are perturbed by levels of the (002) and (030) states, respectively, through Coriolis-type interactions. This allows the determination of the band centers of these two dark states. Copyright 1998 Academic Press.

Line Shift Investigations for Different Isotopomers of Carbon Monoxide.

Line shift coefficients for five lines of five different isotopomers in the fundamental band of CO in the spectral region near 2058 cm-1 were measured using a three channel lead salt diode laser spectrometer. The study includes the lines P(3) of 13C17O, R(3) of 13C18O, P(9) of 12C18O, P(10) of 13C16O, and P(21) of 12C16O, and covers collisions with N2, O2, H2, D2, He, Ne, Ar, Kr, and Xe. Line shifts of the isotopomers 13C16O, 12C18O, 13C18O, and 13C17O were determined for the first time. Within the experimental uncertainty no significant dependence of the shift effect on the isotopomer was found. The R-branch line under study shows a smaller line shift coefficient than a P-branch line with a similar rotational quantum number. With increasing mass of the noble gas perturber the absolute size of the shift coefficient increases. Moreover self- and nitrogen-broadening coefficients for the isotopomer lines were determined. Compared to previous measurements no significant deviations between different isotopomers were observed. Copyright 1998 Academic Press.

The Far-Infrared Spectrum of ClNO2 Studied by High-Resolution Fourier-Transform Spectroscopy.

The far-infrared spectrum of nitryl chloride was studied using high-resolution Fourier-transform spectroscopy in the 300-525 cm-1 region. Vibrational band centers of fundamental, hot, and difference bands were determined. Furthermore, rotational and centrifugal distortion constants up to fourth order for the nu3 bands of 35ClNO2 and 37ClNO2 (centered at 370 and 364 cm-1, respectively) were obtained. The nu5 fundamental of ClNO2 (predicted around 410 cm-1) is very weak and overlapped by difference bands. Copyright 1998 Academic Press.

High-Resolution Infrared Fourier-Transform Spectroscopy and Rotational Constants of the nu4 Band of BrNO2.

For the first time, high-resolution infrared gas-phase absorption spectra of the BrNO2 molecule were recorded using a Fourier-transform spectrometer. In this paper, the nu4 bands of the 79BrNO2 and 81BrNO2 isotopomers around 1670 cm-1 are investigated. Although the spectra are highly congested, rotational and centrifugal distortion constants for the ground and v4 = 1 states of 79BrNO2 and 81BrNO2 were determined. The results show that BrNO2 is a planar molecule of C2nu symmetry and confirm predictions from a recent ab initio study. Copyright 1998 Academic Press.

N2 Broadening in the 13C16O 2-0 Band around 4167 cm-1

N2 broadening coefficients have been measured for 65 lines of the 13C16O 2-0 band using a Fourier transform spectrometer. These lines are located in the spectral range 4011-4252 cm-1. The spectra were recorded with 99% isotopically pure 13CO in a White-type cell at a resolution of 0.005 cm-1. Voigt profiles convolved with the FTS apparatus function were fitted to the experimental lineshapes using a nonlinear least-squares fit technique. From the fits the Lorentzian HWHM was determined as function of N2 pressure. Pressure broadening coefficients for m between -33 and +34 were obtained with uncertainties of 5.8%. The results are compared to earlier published N2 broadening coefficients and our measurements in the 2-0 band of 12C16O. To our knowledge this is the first investigation of 13CO pressure broadening.