Infrared absorption cross sections for propane (C3H8) in the 3 μm region

Infrared absorption cross sections for propane have been measured in the 3 μm spectral region from spectra recorded using a high-resolution FTIR spectrometer (Bruker IFS 125 HR). The spectra of mixtures of propane with dry synthetic air were recorded at 0.015 cm⁻¹ resolution (calculated as 0.9/MOPD using the Bruker definition of resolution), at a number of temperatures and pressures appropriate for atmospheric conditions. Intensities were calibrated using two propane spectra (recorded at 278 and 293 K) taken from the Pacific Northwest National Laboratory (PNNL) IR database.     

Fourier transform infrared emission spectra of MnH and MnD

Fourier transform infrared emission spectra of MnH and MnD were observed in the ground X⁷Σ⁺ electronic state. The vibration-rotation bands from v = 1 → 0 to v = 3 → 2 for MnH and from v = 1 → 0 to v = 4 → 3 for MnD were recorded at an instrumental resolution of 0.0085 cm⁻¹. Spectroscopic constants were determined for each vibrational level and equilibrium constants were found from a Dunham-type fit. The equilibrium vibrational constant (ω_e) for MnH was found to be 1546.84518(65) cm⁻¹, the equilibrium rotational constant (B_e) is 5.6856789(103) cm⁻¹ and the eqilibrium bond distance (r_e) was determined to be 1.7308601(47) Å.     

Fourier Transform Emission Spectroscopy of the Low-Lying Electronic States of NbN

The high-resolution spectrum of NbN has been investigated in emission in the 3000-15 000 cm(-1) region using a Fourier transform spectrometer. The bands were excited in a microwave discharge through a mixture of NbCl(5) vapor, approximately 5 mTorr of N(2), and 3 Torr of He. Numerous bands observed in the near-infrared region have been classified into the following transitions: f(1)Phi-c(1)Gamma, e(1)Pi-a(1)Delta, C(3)Pi(0+)-A(3)Sigma(-)(1), C(3)Pi(0-)-A(3)Sigma(-)(1), C(3)Pi(1)-a(1)Delta, C(3)Pi(1)-A(3)Sigma(-)(0), d(1)Sigma(+)-A(3)Sigma(-)(0), and d(1)Sigma(+)-b(1)Sigma(+). These observations are consistent with the energy level diagram provided by laser excitation and emission spectroscopy [Y. Azuma, G. Huang, M. P. J. Lyne, A. J. Merer, and V. I. Srdanov, J. Chem. Phys. 100, 4138-4155 (1993)]. The missing d(1)Sigma(+) state has been observed for the first time and its spectroscopic parameters are consistent with the theoretical predictions of S. R. Langhoff and W. Bauschlicher, Jr. [J. Mol. Spectrosc. 143, 169-179 (1990)]. Rotational analysis of a number of bands has been obtained and improved spectroscopic parameters have been extracted for the low-lying electronic states. The observation of several vibrational bands with v = 1 has enabled us to determine the vibrational intervals and equilibrium bond lengths for the A(3)Sigma(-)(0), a(1)Delta, b(1)Sigma(+), d(1)Sigma(+), and C(3)Pi(1) states. Copyright 2000 Academic Press.     

Fourier Transform Spectroscopy of the A'(1)Pi-X(1)Sigma(+) System of CaO

The A'(1)Pi-X(1)Sigma(+) near-infrared system of CaO was observed for the first time at high resolution using a Fourier transform spectrometer. The A'(1)Pi-X(1)Sigma(+) chemiluminescence was excited in a Ca + N(2)O flame produced in a Broida-type oven. More than 3000 rotational lines, classified into 19 bands involving the A'(1)Pi 0 /= 2) levels with the nearby b(3)Sigma(+) (v-2) levels has been detected. An extended set of A'(1)Pi (v = 0-3) data has been obtained which is suitable for use in a future multistate deperturbation analysis of the a(3)Pi approximately A'(1)Pi approximately b(3)Sigma(+) approximately A(1)Sigma(+) complex of excited states. The new near-infrared spectra of the A'(1)Pi-X(1)Sigma(+) transition of CaO also permits the first direct high-resolution linkage between the orange and green systems and the near-infrared bands. Copyright 2000 Academic Press.     

High resolution laser excitation spectroscopy of barium monosulfide

High-resolution spectra of BaS were recorded using laser excitation spectroscopy. BaS molecules were synthesized in a Broida-type oven. The observed rotationally-resolved spectrum of BaS in the 12 100–12 765 cm^?1 spectral range contains the 2-1, 3-1, 3-2, 4-2, 5-2, 5-3 vibrational bands of the A′¹Π–X¹Σ⁺ transition and the 4-1, 5-1, 5-2 vibrational bands of the a³Π₁–X¹Σ⁺ transition. Approximately 1000 lines of the A′¹Π–X¹Σ⁺ transition and 600 lines of the a³Π₁–X¹Σ⁺ transition for the main isotopologue ¹³⁸Ba³²S (67.5% natural abundance) were measured. Rotational and vibrational parameters were derived for the A′¹Π and a³Π₁ states.     

Observation of the v = 1 ← 0 band of SH (X2Π) with a difference frequency laser

The fundamental vibration-rotation band of SH (X²Π) has been studied in absorption at Doppler-limited resolution with an estimated accuracy of 0.002 cm^?1. The band origin (ν₀ = 2598.7675 ± 0.0003 cm^?1) and the molecular constants for the excited vibrational state (v = 1), as well as improved molecular constants for the ground vibrational state, have been determined in a least-squares fit.     

Fourier transform spectroscopy of the AΠ-XΣ transition of NH

The A³Π-X³Σ⁻ transition of NH has been observed using a high-resolution Fourier transform spectrometer. The first three vibrational levels in each state were observed and the vibrational, fine structure, and rotational constants obtained.     

Experimental calibration and field investigation of the oxygen isotopic fractionation between biogenic aragonite and water

Marine molluscs have long been recognised as potential records of palaeoclimate change using the patterns and differences in the stable isotopic composition of the carbonate shells. The aim of this study is to improve the robustness of this approach for aragonitic molluscs by completing the first experimental calibration of the fractionation between water and biogenic aragonite. Fractionation factors were calibrated by growing specimens of the freshwater mollusc Lymnaea peregra under controlled conditions of water temperature and isotopic composition. Fifteen populations of L. peregra were maintained at constant temperature and isotopic conditions for five months (at five different temperatures and using three different water compositions). Water samples and temperature measurements were taken regularly throughout the experiment. The temperature dependence of the fractionation factor, between 8 and 24 degrees C, is given by: 1000 ln alpha=16.74x(1000T(-1))-26.39 (T in Kelvin) and the relationship between temperature (T), delta(18)O(carb) and delta(18)O(wat) is given by: T=21.36-4.83xdelta(+ degrees )O(carb)-delta(+ degrees )O(wat) (T is in degrees C, delta(18)O(carb) is with respect to Vienna Pee Dee Belemnite (PDB), the International Atomic Energy Agency (IAEA) replacement standard for PDB, and delta(18)O(wat) is with respect to Vienna standard mean ocean water (VSMOW)) The outcome of the controlled experiment is compared with previous studies on synthetic, and biogenic, calcite and aragonite from field and laboratory investigations. These comparisons suggest that although a vital offset exists between the fractionation of isotopes in synthetic and biogenic aragonite for molluscs in general, there is no vital effect that is specific either to freshwater, or to individual, genera. Therefore, the calibrated relationship may be used for any freshwater or marine mollusc to derive palaeotemperatures providing the isotopic composition of the environmental water can be reliably constrained. Copyright 1999 John Wiley & Sons, Ltd.     

Extension of the angle dependent phase shift formalism to vibrational excitations

The angle dependent phase shift formalism for a permanently deformed target is generalized to include the excitation of vibrational states. In this extension, theS-matrix depends on the intrinsic angle describing the deformed surface as well as on the amplitude of the vibration. Numerical examples are given.     

Non-Voigt line-shape effects on retrievals of atmospheric ozone: Collisionally isolated lines

This paper addresses the question of errors in retrievals of vertical profiles of ozone from atmospheric spectra caused by assuming that the absorption lines have pure Voigt line shapes. The case of collisionally isolated transitions (no line mixing) is treated by considering only the effects of the speed dependence (SD) of the pressure broadening. The case of O₃ retrievals from a sequence of limb transmission spectra is first treated theoretically. The results show that the influence of SD is very small, leading to changes in the residuals and in the retrieved O₃ mixing ratios smaller than 1%. These findings are then confirmed by treating a series of spectra recorded by the ACE-FTS instrument. Similar exercises are also made for other observation techniques by treating simulated or measured limb and nadir emission spectra as well as ground-based solar and in-situ laser transmission data. All lead to the general conclusion that SD (and Dicke narrowing) can be neglected in retrievals of ozone amounts from recorded atmospheric spectra. Indeed, the biases caused in the ozone profiles by the use of pure Voigt line shapes still remain significantly smaller than the total error/uncertainty from other sources such as improper line intensities and widths, uncertainty in the instrument function, errors in the pressure and temperature profiles and so forth.