XUV laser studies of Rydberg-valence states in N2 and H+H- heavy Rydberg states

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A Rayleigh-Brillouin scattering spectrometer for ultraviolet wavelengths

A spectrometer for the measurement of spontaneous Rayleigh-Brillouin (RB) scattering line profiles at ultraviolet wavelengths from gas phase molecules has been developed, employing a high-power frequency-stabilized UV-laser with narrow bandwidth (2 MHz). The UV-light from a frequency-doubled titanium: sapphire laser is further amplified in an enhancement cavity, delivering a 5 W UV-beam propagating through the interaction region inside a scattering cell. The design of the RB-scattering cell allows for measurements at gas pressures in the range 0-4 bars and at stably controlled temperatures from -30 degrees C to 70 degrees C. A scannable Fabry-Perot analyzer with instrument resolution of 232 MHz probes the RB profiles. Measurements on N-2 and SF6 gases demonstrate that the high signal-to-noise ratio is achievable with the instrument at the 1% level at the peak amplitude of the scattering profile. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4721272

HD as a probe for detecting mass variation on a cosmological time scale

The strong electronic absorption systems of the B-1 Sigma(+)(u)-X-1 Sigma(+)(g) Lyman and the C-1 Pi(u)-X-1 Sigma(+)(g) Werner bands can be used to probe possible mass-variation effects on a cosmological time scale from spectra observed at high redshift, not only in H-2 but also in the second most abundant hydrogen isotopomer HD. High resolution laboratory determination of the most prominent HD lines at extreme ultraviolet wavelengths is performed at an accuracy of Delta lambda/lambda similar to 5x10(-8), forming a database for comparison with astrophysical data. Sensitivity coefficients K-i=dln lambda(i)/dln mu are determined for HD from quantum ab initio calculations as a function of the proton-electron mass ratio mu. Strategies to deduce possible effects beyond first-order baryon/lepton mass ratio deviations are discussed

Extreme ultraviolet laser calibration of D-2 Lyman and Werner transitions

- X-1 Sigma(+)(g)(0,0) Werner band of the D-2 molecule were measured using a narrowband tunable extreme-ultraviolet laser source, at an unprecedented accuracy of Delta lambda/lambda = 6 x 10(-8). The results bear relevance for future use in the calibration of dense classical spectra obtained for the HD and D-2 hydrogen isotopologues

Frequency calibration of B (1)Sigma(+)(u)-X (1)Sigma(+)(g) (6,0) Lyman transitions in H-2 for comparison with quasar data

The Lyman and Werner spectroscopic transitions of molecular hydrogen, the most ubiquitous molecular spectral lines observed in the universe, provide a tool to probe a possible variation of the proton-to-electron mass ratio mu on a cosmological time scale. Such procedures require a database of zero-redshift, or laboratory-based wavelengths at the highest possible level of accuracy. Accurate transitions in the B (1)Sigma(+)(u)-X (1)Sigma(+)(g) (6,0) Lyman band of H2 are still missing in the set of laboratory data, due to previously encountered problems in generating the appropriate wavelengths using a narrow-band extreme ultraviolet laser source. Here frequency calibrations of the missing transitions are presented from a laser-based study at a (5 - 8) x 10(-8) accuracy level

On the complexity of the absorption spectrum of molecular nitrogen

The spectral properties of molecular nitrogen are crucial to a better understanding of radiative-transfer phenomena and activated N/

On the complexity of the absorption spectrum of molecular nitrogen

The spectral properties of molecular nitrogen are crucial to a better understanding of radiative-transfer phenomena and activated N/N2 chemistry in the Earth's upper atmosphere. Excited states of N2 are difficult to access experimentally, and analysis o

Observation of a Rydberg Series in H+H-: A Heavy Bohr Atom

We report on the realization of a heavy "Bohr atom," through the spectroscopic observation of a Rydberg series of bound quantum states at principal quantum numbers n=140 to 230. The system is made heavy by replacing an electron inside a hydrogen atom by a composite H- particle, thus forming a H+H- Coulombically bound system obeying the physical laws of a generalized atom with appropriate mass scaling. © 2008 The American Physical Society