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The high-resolution B$^1\Sigma^+$ - A$^1\Pi$ (0, 0) and (0, 3) emission bands of the less-abundant $^{13}$C$^{17}$O isotopologue have been investigated by Fourier-transform spectroscopy in the visible region using a Bruker IFS 125HR spectrometer at an accuracy 0.003 cm$^{-1}$. These spectra are combined with high-resolution photoabsorption measurements of the $^{13}$C$^{17}$O B$^1\Sigma^+$ $\leftarrow$ X$^1\Sigma^+$ (0, 0), B$^1\Sigma^+$ $\leftarrow$ X$^1\Sigma^+$ (1, 0) and C$^1\Sigma^+$ $\leftarrow$ X$^1\Sigma^+$ (0, 0) bands recorded with an accuracy of 0.01 cm$^{-1}$ using the vacuum ultraviolet Fourier-transform spectrometer, installed on the DESIRS beamline at the SOLEIL synchrotron. In the studied 17,950 - 22,500 cm$^{-1}$ and 86,800 - 92,100 cm$^{-1}$ regions, 480 transitions have been measured. These new experimental data were combined with data from the C $\to$ A and B $\to$ A systems, previously analyzed in 13C17O. The frequencies of 1003 transitions derived from 12 bands were used to analyze the perturbations between the A$^1\Pi$ ($\nu$ = 0 - 3) levels and rovibrational levels of the d$^3\Delta_i$, e$^3\Sigma^-$, a$'{}^3\Sigma^+$, I$^1\Sigma^-$ and D$^1\Delta$ states as well as to a preliminary investigation of weak irregularities that appear in the B$^1\Sigma^+$ ($\nu$ = 0) level. Deperturbed molecular constants and term values of the A$^1\Pi$ state were obtained. The spin-orbit and L-uncoupling interaction parameters as well as isotopologue-independent spin-orbit and rotation-electronic perturbation parameters were derived., Comment: 37 pages, 8 tables, 7 figures, 91 references

High-accuracy dispersive optical spectroscopy measurements in the visible (VIS) region have been performed on the less-abundant 12C17O isotopologue, observing high-resolution emission bands of the B1Σ+ (υ = 0) → A1Π (υ = 3, 4, and 5) Angstrom system. These are combined with high-resolution photoabsorption measurements of the 12C17O B1Σ+ (υ = 0) ← X1Σ+ (υ = 0) and C1Σ+ (υ = 0) ← X1Σ+ (υ = 0) Hopfield–Birge bands recorded with the vacuum-ultraviolet (VUV) Fourier transform spectrometer, installed on the DESIRS beamline at the SOLEIL synchrotron. The frequencies of 429 observed transitions have been determined in the 15 100–18 400 cm−1 and 86 900–92 100 cm−1 regions with an absolute accuracy of up to 0.003 cm−1 and 0.005 cm−1 for the B–A, and B–X, C–X systems, respectively. These new experimental data were combined with data from the previously analysed C → A and B → A systems. The comprehensive data set, 982 spectral lines belonging to 12 bands, was included in a deperturbation analysis of the A1Π, υ = 1–5 levels of 12C17O, taking into account interactions with levels in the d3Δi, e3Σ−, a′3Σ+, I1Σ− and D1Δ states. The A1Π and perturber states were described in terms of a set of deperturbed molecular constants, spin–orbit and L-uncoupling interaction parameters, equilibrium constants, 309 term values, as well as isotopologue-independent spin–orbit and rotation-electronic perturbation parameters.

Our knowledge of astronomical environments containing CO depends on accurate molecular data to reproduce and interpret observed spectra. The recent and future improvements of ultraviolet space instrumentation, both in sensitivity and resolution, require increasingly detailed laboratory molecular spectroscopy as a reference. As part of a long-term experimental campaign at the SOLEIL Synchrotron facility, we have acquired gas-phase absorption spectra of six CO isotopologues in the vacuum ultraviolet. These spectra are recorded using the Fourier-transform spectrometer installed on the DESIRS beamline, providing a unique resolving power up to 106 in the 8–13 eV range. We have used resolutions in the 300 000–450 000 range for this campaign, which enable the analysis of individual line positions. We report new measurements on neighboring Rydberg states in the 101–115 nm range that could also be used as f-value calibrators, namely B1Σ+, C1Σ+, and E1Π, for six CO isotopologues. This range encompasses the absorption transitions B(v′ = 0, 1, and 2), C(v′ = 0, 1, 2, and 3), and E(v′ = 0, 1, 2, and 3) from X1Σ+(v′′ = 0). Higher resolution laser-based measurements of CO isotopologues from the literature are used to improve the absolute calibration and accuracy of our data. The overall uncertainty of the great majority of the line positions presented in this atlas is estimated to be 0.01 cm−1. In addition, some of the data derived from transition energies measurements, such as term values and molecular constants, are obtained for the first time, and others are improvements on previous sparser or lower spectral resolution datasets.

The photochemistry of CO and its isotoplogues affects the structure and evolution of many astronomical environments, including interstellar clouds, circumstellar disks around newly formed stars, and the envelopes surrounding highly evolved stars. When in the presence of a strong ultraviolet field, the primary destruction mechanism for interstellar and circumstellar CO is photodissociation, which is entirely governed by discrete line absorption into predissociating levels in the wavelength range 91.2 to 111.8 nm. Because the CO spectrum consists primarily of resolved line features, self-shielding effects in high-column density environments can lead to strong isotopic fractionation signatures in both CO and elemental oxygen and carbon; for example, CO self-shielding in the solar nebula has been invoked to explain the unusual oxygen isotope ratios observed in the earliest solar system condensates, viz. calcium-aluminum inclusions (CAIs) in primitive meteorites.

One of the processes controlling the interstellar CO abundance and the ratio of its isotopologues is photodissociation. Accurate oscillator strengths and predissociation rates for Rydberg transitions are needed for modeling this process. We present results on absorption from the E ^1Pi-X ^1Sigma^+ (1-0) and B ^1Sigma^+-X ^1Sigma^+ (6-0) bands at 1051 and 1002 \AA, respectively, and the vibrational progression W ^1Pi-X ^1Sigma^+ (v'-0) bands with v' = 0 to 3 at 972, 956, 941, and 925 \AA, respectively. The corresponding spectra were acquired at the high resolution (R ~ 30,000) SU5 beam line at the Super ACO Synchrotron in Orsay, France. Spectra were obtained for the ^12C^16O, ^13C^16O, and ^13C^18O isotopologues. These represent the most complete set of measurements available. Comparison is made with earlier results, both empirical and theoretical. While earlier determinations of oscillator strengths based on absorption from synchrotron radiation tend to be somewhat smaller than ours, the suite of measurements from a variety of techniques agree for the most part considering the mutual uncertainties. For the bands studied here, their relative weakness, or their significant line widths arising from predissociation, minimizes potential problems from large optical depths at line center in absorption measurements. Predissociating line widths could generally be extracted from the spectra thanks to the profile simulations used in the analysis. In many cases, these simulations allowed us to consider e and f parity levels separately and to determine the dependence of the width on rotational quantum number, J. Our results are consistent with earlier determinations, especially the widths inferred from laser experiments.

Absorption oscillator strengths have been determined from high-resolution spectra in the 967-972 \AA region of three CO isotopomers for transitions to the Rydberg levels 4{\it p$\pi$}(0), 3{\it d$\pi$}(1) and 4{\it p$\sigma$}(0), as well as to the mixed {\it E(6)} level recently characterized by Eidelsberg et al. (2004). Synchrotron radiation from the Super-ACO electron storage ring at Orsay (LURE) was used as a light source. Oscillator strengths were extracted from the recorded spectra by least-squares fitting of the experimental profiles with synthetic spectra taking into account the homogeneous and heterogeneous interactions of the four levels. Column densities were derived from fits to the 3{\it p$\pi$}(0) absorption band whose oscillator strength is well established. These are the first reported measurements for $^{13}$C$^{18}$O. For $^{12}$C$^{16}$O, our results are consistent with the larger values obtained in the most recent laboratory and astronomical studies.

The forbidden triplet-singlet bands of CO, originating from the X 1Σ+(v = 0) level and involving the a'3Σ+, e3Σ-, and d3Δ states, can advantageously be used in view of their low oscillator strengths to measure large CO column densities when the allowed A 1Π(v) - X 1Σ+(0) bands are saturated. The line positions and intensities of 41 of these bands are tabulated up to j = 6 in the paper version and up to J = 33 in electronic form. These data were obtained using an improved model developed in a previous paper. When possible, the calculated results are compared to experimental or observed ones, both for line positions and for oscillator strengths. The measured band oscillator strengths average to 94% of the calculated ones. A large majority of the measured values (27 out of 35) are within ±15% of the calculated ones. Thus, in view of the experimental uncertainties, it appears that the current calculated set of oscillator strengths can safely be used for the analysis of future absorption spectra involving the CO intercombination bands.

We observe photoabsorption of the W(1) ← X(0) band in five carbon monoxide isotopologues with a vacuum-ultraviolet Fourier-transform spectrometer and a synchrotron radiation source. We deduce transition energies, integrated cross sections, and natural linewidths of the observed rotational transitions and find a perturbation affecting these. Following a deperturbation analysis of all five isotopologues, the perturbing state is assigned to the v = 0 level of a previously unobserved (1)Π state predicted by ab initio calculations to occur with the correct symmetry and equilibrium internuclear distance. We label this new state E″ (1)Π. Both of the interacting levels W(1) and E″(0) are predissociated, leading to dramatic interference effects in their corresponding linewidths.

The forbidden c3Π–X1Σ+ (0–0) absorption band of carbon monoxide has been reinvestigated under different pressure conditions using the 10.7-m VUV spectrograph at Meudon. Overlap with the allowed C1Π–X1Σ+ (0–0) band at lower transition energy has been taken into account. We have identified a new rotational branch corresponding to an S-type branch and extended the analysis to both higher and lower J. An analysis of the band structure and the low J transition lines suggests that the band gains its intensity predominantly as a result of an interaction of the c3Π state with a 1Σ+ state, most likely the C1Σ+ (v = 0) state. Molecular constants have been obtained for the c3Π state that are in reasonable agreement with those previously published. The apparently anomalous small value for the centrifugal distortion constant is explained by a homogeneous perturbation with the k3Π valence state.

Absorption oscillator strengths of 18 intersystem bands of CO between 1360 and 1620 A originating from the ground state and involving the a′ 3Σ+, e 3Σ−, and d 3Δ states have been measured using synchrotron radiation as a background source. They have also been calculated using the published molecular parameters provided by the standard spectroscopic perturbation analysis, including the spin-orbit interaction with the nearby A 1Π state. It was found, however, that the model used in that analysis had to be extended in order to take into account the contributions of several vibrational levels of the A state to the intensity of a given singlet–triplet band. The present measurements are in good agreement with the predictions of this extended model. The puzzling discrepancies reported earlier between oscillator strength or rotationally resolved lifetime measurements and standard calculations are now well understood as well as the temperature variation of some of these band-integrated oscillator strengths. Line a...

Our knowledge of astronomical environments containing CO depends on accurate molecular data to reproduce and interpret observations. The constant improvement in UV space instrumentation, both in sensitivity and resolution, requires increasingly detailed laboratory data. Following a long-term experimental campaign at the SOLEIL Synchrotron facility, we have acquired complete datasets on the CO isotopologues in the vacuum ultraviolet. Absorption spectra were recorded using the Fourier-transform spectrometer installed on the DESIRS beamline, providing a resolving power R > 106 in the 8–12 eV range. Such resolution allows the analysis of individual line positions and strengths in electronic transitions and the location of perturbations. We continue our previous work on A–X bands of 12C16O and 13C16O, reporting here measurements for the 13C18O isotopologue.

A review of the 1 Π–X 1 Σ + transitions observed in the extreme ultra violet spectra from 92 000 to 105 500 cm −1 of four CO isotopologs is presented. It is based both from previous and new experiments. A theoretical model is suggested to assign all the 1 Π observed levels in terms of four Rydberg states interacting with the E′ 1 Π valence state. This is made by solving a set of five coupled Schrodinger equations. The agreement between theory and experiment is reasonable.

A supersonic pulsed jet for high-resolution studies of rotationally cold molecules was constructed at the 10.6 m vacuum UV spectrograph of the Observatoire de Meudon. The background continuum for photographic absorption work is emitted from a pulsedBalloffet–Romand–Vodar (BRV) source (vacuum spark). The new apparatus has been used to record the absorption spectra of the four main isotopomers of CO from 880 to 1110 Å (1 Å = 10−10 m). First results of the analysis help to clarify the rovibronic structure in two specific regions of the spectrum (103 000–103 300 and 109 300–109 600 cm−1) and are relevant to the discussion of 1Σ+–1Σ+ and 1Π–1Π homogeneous interactions of CO.

Rotationally integrated vibrational absorption cross sections of the A 1Π−X 1Σ+ (v’−0) bands of CO have been measured in the wavelength range 125–155 nm using monochromatized synchrotron radiation as background light source. Absorption cross sections for a few singlet‐triplet transitions are also obtained. Vibrational band oscillator strengths are determined for 0≤v’≤12 and compared to other experimental and theoretical values. It is found that the new data are well reproduced by extrapolating to shorter internuclear distances the parabolic dipole transition moment function determined by De Leon [J. Chem. Phys. 89, 20 (1988); 91, 5859 (1989)]. Deperturbed lifetimes for levels 0≤v’≤13 are calculated from the parabolic dipole moment function and, except for v’=13, are found in good agreement with available experimental results.

A.H. was supported by Grant No. 648.000.002 from the Netherlands Organisation for Scientific Research (NWO) via the Dutch Astrochemistry Network. This research was supported by funds from National Aeronautics and Space Administration (NASA) (Grant Nos. NNX09AC5GG to Wellesley College and NNG 06- GG70G and NNX10AD80G to the University of Toledo), CNRS (France), and Programme National Physico-Chimie du Milieu Interstellaire (PCMI). L.G. and J.L.L. acknowledge the financial support of the European Community 7th Framework Programme (FP7/2007-2013) Marie Curie ITN under Grant Agreement # 238258.

Models of astronomical environments containing CO require accurate molecular data to reproduce and interpret observations. We conduct experiments at the SOLEIL synchrotron facility to acquire data to model CO photochemistry in the vacuum ultraviolet. The improvement in UV spectroscopic instrumentation in both sensitivity and resolution provides more accurate laboratory spectroscopic determinations. We continue our work on photoabsorption oscillator strengths and predissociation rates for 12 C16 O; we report new measurements for two additional isotopologues, 13 C16 O and 12 C18 O, of four bands from X 1 Σ+ (v′′ = 0) to the v′ = 0–3 vibrational levels of the core-excited W 1 Π Rydberg state and for four overlapping bands (three resolved and one diffuse) between 92.97 and 93.35 nm. Some of the latter include unidentified perturbations. Absorption spectra were recorded using the vacuum-ultraviolet Fourier-transform spectrometer that is installed on the DESIRS beamline at SOLEIL which provides a resolving power R = 350 000. This resolution allows the analysis of individual line strengths and widths in the electronic transitions and the identification of a previously unobserved perturbation in the W(1) level. Gas column densities in the differentially-pumped system were calibrated using the B 1 Σ+ – X 1 Σ+ (v′ = 0,v′′ = 0) band. Absorption bands are analyzed by synthesizing line and band profiles and fitting them to the measured spectra. These considerably improved results are compared with earlier determinations.

We report oscillator strengths for six strong vibrational bands between 105.0 and 115.2 nm, associated with transitions from the v = 0 level of the X 1Σ+ ground state to the v = 0 and 1 levels of the B 1Σ+, C 1Σ+, and E 1Π states, in 12C16O, 12C17O, 12C18O, 13C16O, and 13C18O. These measurements extend the development of a comprehensive database of line positions, oscillator strengths, and linewidths of photodissociating transitions for all astrophysically relevant CO isotopologues. The E-X bands, in particular, play central roles in CO photodissociation and fractionation models of interstellar clouds and circumstellar disks including the early solar nebula. The resolving powers of the room-temperature measurements, R = 300,000-400,000, allow for the analysis of individual line strengths within bands; the measurements reveal J-dependences in the branch intensities of the C(v = 0,1)-X(0) and E(v = 0,1)-X(0) bands in all isotopologues. Minimal or no isotopologue dependence was found in the f-values of the C(v = 0,1)-X(0) and E(v = 0,1)-X(0) bands at a ~5% uncertainty level. Revised dissociation branching ratios for the C(v = 0,1) and E(v = 0,1) levels are computed based on these f-values. The weak isotopologue dependence of the f-values presented here eliminates this mechanism as an explanation for the large 17O enrichments seen in recent laboratory photolysis experiments on CO at wavelengths from 105 to 108 nm.

Rotationally cold absorption and two-photon ionization spectra of CO in the 90–100 nm region have been recorded at a resolution of 0.3–1.0 cm−1. The analyses of up to four isotopomers seek to clarify the observations in regions where the Rydberg levels built on the ground state X 2Σ+ of the ion interact with valence states of 1Σ+ and 1Π symmetry. Previous observations of the 3sσ, B 1Σ+ Rydberg state, reviewed by Tchang-Brillet et al. [J. Chem. Phys. 96, 6735 (1992)], have been extended to energies above its avoided crossing with the repulsive part of the D′ 1Σ+ valence state where resonances of varying intensities and widths have been attributed to the fully coupled 3sσ or 4sσ and D′ potentials, and where the B state approaches a second avoided crossing with the C′ 1Σ+ valence state [Cooper and Kirby, J. Chem. Phys. 87, 424 (1987); 90, 4895 (1989); Chem. Phys. Lett. 152, 393 (1988)]. Fragments of a progression of weak and mostly diffuse bands, observed for all four isotopomers, have been assigned to the C...

The vacuum ultraviolet band spectrum system B1Σ+-X1Σ+ of 12C16O, 13C16O, 12C18O, and 13C18O has been extensively investigated both in absorption and in emission with the Meudon Observatory national 10-m vacuum spectrograph. A band lying at 109.9 nm in 12C16O is observed for all isotopes but only in absorption. It is shown to be the B-X(2-0) band. Molecular parameters of the B(v = 0, 1, 2) levels have been derived from simultaneous least-squares fits of the absorption and emission data pertaining to each of these vibrational levels. In addition, a simultaneous fit of the data for the different isotopes provided mass independent Dunham coefficients and equilibrium constants for the B state. Our values obtained for ωe and ωexe confirm the recent determinations which are in disagreement with the values tabulated in standard references. The emission bands exhibit sudden weakenings typical of predissociation. This predissociation further manifests itself in the v = 2 level by a conspicuous broadening of the absorption lines. It may also be the cause of the displacement and anomalous B values observed for this level. From the Dunham coefficients, the following molecular constants (in cm−1 except for re) for the B state have been derived: T e =86926.9 r 3 =1.1197 A . ω e ω e x e B e α e 10 6 D e 12C16O 2161.75 39.84 1.9613 0.0262 6.5 13C16O 2113.56 38.08 1.8749 0.0245 6.0 12C18O 2109.53 37.93 1.8677 0.0244 5.9 13C18O 2060.12 36.18 1.7812 0.0227 5.4 14C16O 2071.52 36.58 1.8010 0.0231 5.5

The spectrum of the helium-like boron ion B IV has been obtained by using the laser-impact technique. It has been recorded in the 250-4500 AA wavelength region. The ionization energy has been determined to be 2091976+or-20 cm-1, by means of the theoretical values for the np 1P energy levels. Experimental values of the Lamb shift have been determined for the ground state (-93+or-20 cm-1) and for the two first excited levels 2s 1S and 2s 3S (-8.0 cm-1 and -8.6 cm-1 respectively). The term system is derived from twenty two new lines and extended by using Ritz formulae and other semi-empirical formulae. The results are compared with theoretical calculations of ionization energies.

The gas-phase absorption spectra of 12CO2 and 13CO2 have been photographed between 880 and 2000 A at a resolution of 0.008 A. The diffuse character of most of the bands in this region was confirmed, but the considerable increase in resolution (× 25) over previous work has enabled us to observe some rotationally resolved bands. Our results show that some previous band assignments in the vacuum ultraviolet spectra of CO2 must be revised. Analysis of the 1106 A band of both isotopic species provides molecular constants for its upper electronic state, which is shown to be linear. The 1106 A band is assigned as the origin of the Rydberg forbidden transition ⋯π3g33pπu3Σ–uâ†�X1Σ+g of CO2. The v2 bending vibration of the 3Σ–u state is found to have a value of 498 cm–1 in 12CO2(483 cm–1 in 13CO2) from assignment of the 211 transition. Our results are used to interpret some aspects of the excitation spectrum and yield of CO2 photodissociation.

Cross sections for photoabsorption and photodissociation of CO between 88.5 and 115 nm have been measured at a spectral resolution of 0.015 nm using a synchrotron radiation source. Most of the photodissociation is found to occur in rotationally resolved bands and not in continua. The region below 100 nm predominates in the photodissociation rate. The band absorption cross sections of the first Rydberg states are considerably increased with respect to previous studies following a better appreciation of pressure saturation effects. The integrated photodissociation cross section above 91.2 nm, which is of interest in many astrophysical situations, is measured to be 300 ± 40 × 10 −18 cm 2 nm, sharply increased with respect to usually accepted values.

The spectrum of five-times ionized phosphorus (P VI) is observed in the 400-1 500 Å wavelength range. A total of 76 new lines are measured and classified as transitions between the 2p 53s, 3p, 3d and 4f configurations. All energy levels in these configurations are determined. Their identification is supported by the results of parametric calculations and by an isoelectronic comparison.

The spectrum of Be III has been studied in the wavelength region 80-6200AA. The energy of the ground state 1s21S0 has been determined as 1241253+or-10cm-1 below the first ionization limit. Members of the ns, np, nd, nf series have been identified as well as one 5g term. About 30 Be III lines are classified and good agreement is obtained with existing theoretical calculations.

The spectrum of S VII has been observed between 500 and 1200 Å using the beam-foil excitation and the triggered-spark source. Twelve new lines have been observed and classified as transitions between 2p 5 3s, 3p and 3d configurations. Energies and designations are given for 12 new levels of these configurations. Lifetimes have been measured for 7 levels.