E.J. Salumbides

High resolution spectroscopy and perturbation analysis of the CO A1Π −X1Σ+ (0,0) and (1,0) bands

The two lowest-v′ (0,0) and (1,0) bands of the A1Π −X1Σ+ system of 12C16O have been investigated by two high-resolution spectroscopic methods. A vacuum ultraviolet Fourier-transform spectrometer, illuminated by synchrotron radiation, was applied to record a jet-cooled spectrum and a room temperature static gas spectrum, resulting in absolute accuracies of 0.01−0.02 cm−1. In addition two-photon Doppler-free laser spectroscopy has been applied to a limited number of rotational lines, resulting in an accuracy of 0.002 cm−1. The data were used to perform an improved analysis of the perturbations in the A1Π, v = 0 and v = 1 levels by vibrational levels in the D1Δ, I1Σ−, e3Σ−, d3Δ. and a′3Σ+ states.

Constraints on extra dimensions from precision molecular spectroscopy

Accurate investigations of quantum-level energies in molecular systems are shown to provide a testing ground to constrain the size of compactified extra dimensions. This is made possible by recent progress in precision metrology with ultrastable lasers on energy levels in neutral molecular hydrogen (H2, HD, and D2) and molecular hydrogen ions (H2+, HD+, and D2+). Comparisons between experiment and quantum electrodynamics calculations for these molecular systems can be interpreted in terms of probing large extra dimensions, under which conditions gravity will become much stronger. Molecules are a probe of spacetime geometry at typical distances where chemical bonds are effective (i.e., at length scales of an ?). Constraints on compactification radii for extra dimensions are derived within the Arkani-Hamed-Dimopoulos-Dvali framework, while constraints for curvature or brane separation are derived within the Randall-Sundrum framework. Based on the molecular spectroscopy of D2 molecules and HD+ ions, the compactification size for seven extra dimensions (in connection to M-theory defined in 11 dimensions) of equal size is shown to be limited to . While limits on compactification sizes of extra dimensions based on other branches of physics are compared, the prospect of further tightening constraints from the molecular method is discussed.

High-precision laser spectroscopy of the CO A1Π - X1Σ+ (2,0), (3,0), and (4,0) bands

High-precision two-photon Doppler-free frequency measurements have been performed on the CO A(1)Π - X(1)Σ(+) fourth-positive system (2,0), (3,0), and (4,0) bands. Absolute frequencies of forty-three transitions, for rotational quantum numbers up to J = 5, have been determined at an accuracy of 1.6 × 10(-3) cm(-1), using advanced techniques of two-color 2u2009 + u20091 resonance-enhanced multi-photon ionization, Sagnac interferometry, frequency-chirp analysis on the laser pulses, and correction for AC-Stark shifts. The accurate transition frequencies of the CO A(1)Π - X(1)Σ(+) system are of relevance for comparison with astronomical data in the search for possible drifts of fundamental constants in the early universe. The present accuracies in laboratory wavelengths of Δλ/λ = 2 × 10(-8) may be considered exact for the purpose of such comparisons.

Spectroscopy and perturbation analysis of the CO A

ABSTRACT The (2,0) (3,0) and (4,0) bands of the A1Π −X1Σ+ system of 12C16O have been re-investigated by high-resolution vacuum ultraviolet absorption spectroscopy. A vacuum ultraviolet Fourier-transform spectrometer, illuminated by synchrotron radiation, was applied to record a jet-cooled spectrum, a room temperature static gas spectrum and a high-temperature (900 K) quasi-static gas spectrum, resulting in absolute accuracies of 0.01−0.02 cm−1 for the rotational line frequencies. Precise laser-based data were included in the analysis allowing for a highly accurate determination of band origins. Rotational levels up to J = 52 were observed. The data were used to perform an improved analysis of the perturbations in the A1Π, v = 2, v = 3 and v = 4 levels by vibrational levels of the D1Δ, I1Σ−, e3Σ−, d3Δ and a′3Σ+ states.

^1\Pi-

Precision measurements are performed on highly excited vibrational quantum states of molecular hydrogen. The v = 12, J = 0 - 3 rovibrational levels of H2 (X(1)Σg (+)), lying only 2000 cm(-1) below the first dissociation limit, were populated by photodissociation of H2S and their level energies were accurately determined by two-photon Doppler-free spectroscopy. A comparison between the experimental results on v = 12 level energies with the best ab initio calculations shows a good agreement, where the present experimental accuracy of 3.5 × 10(-3) cm(-1) is more precise than theory, hence providing a gateway to further test theoretical advances in this benchmark quantum system.

X

Abstract Photoabsorption spectra of N2 and CO were recorded at 900xa0K, using the vacuum-ultraviolet Fourier-transform spectrometer at the DESIRS beamline of synchrotron SOLEIL. These high-temperature and high-resolution measurements allow for precise determination of line wavelengths, oscillator strengths, and predissociative line broadening of highly-excited rotational states with J up to about 50, and also vibrational hot bands. In CO, the perturbations of the A 1 Π - X 1 Σ + vibrational bands ( 0 , 0 ) and ( 1 , 0 ) were studied, as well as the transitions to perturbing optically-forbidden states e 3 Σ - , d 3 Δ , D 1 Δ and a ′ 3 Σ + . In N2, we observed line shifts and broadening in several b 1 Π u - X 1 Σ g + bands due to unobserved forbidden states of 3 Π u symmetry. The observed state interactions are deperturbed and, for N2, used to validate a coupled-channels model of the interacting electronic states. These data are appropriate for use in astrophysical or (exo-)planetary atmospheric applications where high temperatures are important and in future spectroscopic models of these molecules.Accurate experimental values for the vibrational ground tone or fundamental vibrational energy splitting of H2, HD, and D2 are presented. Absolute accuracies of 2×10 −4 cm are obtained from Doppler-free laser spectroscopy applied in a collisionless environment. The vibrational splitting frequencies are derived from the combination difference between separate electronic excitations from the XΣg , v = 0, J and v = 1, J vibrational states to a common EF Σg , v = 0, J state. The present work on rotational quantum states J = 1, 2 extends the results reported by Dickenson et al. on J = 0 [Phys. Rev. Lett. 110 (2013) 193601]. The experimental procedures leading to this high accuracy are discussed in detail. A comparison is made with full ab initio calculations encompassing Born-Oppenheimer energies, adiabatic and non-adiabatic corrections, as well as relativistic corrections and QED-contributions. The present agreement between the experimental results and the calculations provides a stringent test on the application of quantum electrodynamics in molecules. Furthermore, the combined experimental-theoretical uncertainty can be interpreted to provide bounds to new interactions beyond the Standard Model of Physics or fifth forces between hadrons.

^1\Sigma^+

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 15u2006100–18u2006400 cm−1 and 86u2006900–92u2006100 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.

(2,0), (3,0) and (4,0) bands

The rotationally resolved spectrum of the B 2 P–X 2 P electronic origin band transition of 13 C6H is presented. The spectrum is recorded using cavity ring-down spectroscopy in combination with supersonic plasma jets by discharging a 13 C2H2/He/Ar gas mixture. A detailed analysis of more than a hundred fully-resolved transitions allows for an accurate determination of the spectroscopic parameters for both the ground and electronically excited state of 13 C6H.

Communication: Test of quantum chemistry in vibrationally hot hydrogen molecules.

Accurate absolute level energies of the

VUV-synchrotron absorption studies of N-2 and CO at 900 K

B,^1Sigma^{+}_{u}