COMPARATIVE VERY-HIGH-RESOLUTION VUV SPECTROSCOPY: LASER SPECTROSCOPY OF O2

Despite their importance to the photochemistry of the terrestrial atmosphere, and many experimental studies, previous characterization of the Schumann–Runge (SR) bands of O 2, [Formula: see text] (1750–2050 Å) has been limited by poor experimental resolution. In addition, our understanding of the SR spectrum is incomplete, many rovibrational transitions in the perturbed region of the spectrum [B(v > 15)] remaining unassigned. We review new very-high-resolution measurements of the O 2 photoabsorption cross section in the SR bands. Tunable, narrow-bandwidth background vacuum-ultraviolet (VUV) radiation for the measurements (~ 7 × 105 resolving power) was generated by the two-photon-resonant difference-frequency four-wave mixing in Xe of excimer-pumped dye-laser radiation. With the aid of these cross-section measurements, rovibrational and line-shape analyses have led to new insights into the molecular structure and predissociation dynamics of O 2. The current VUV laser-spectroscopic measurements are shown to compare favourably with results from two other very-high-resolution experimental techniques, namely laser-induced fluorescence spectroscopy and VUV Fourier-transform spectroscopy, the latter performed using a synchrotron source.

Download Full-text

Photoionization Cross-Sections of Carbon-Like N+ Near the K-Edge (390–440 eV)

Atoms ◽

10.3390/atoms9020027 ◽

2021 ◽

Vol 9 (2) ◽

pp. 27

Author(s):

Jean-Paul Mosnier ◽

Eugene T. Kennedy ◽

Jean-Marc Bizau ◽

Denis Cubaynes ◽

Ségolène Guilbaud ◽

...

Keyword(s):

High Resolution ◽

Cross Section ◽

Cross Sections ◽

Experimental Studies ◽

Photoionization Cross Section ◽

Theoretical Work ◽

Rydberg Series ◽

R Matrix ◽

Resonance Strengths ◽

Nitrogen Ion

High-resolution K-shell photoionization cross-sections for the C-like atomic nitrogen ion (N+) are reported in the 398 eV (31.15 Å) to 450 eV (27.55 Å) energy (wavelength) range. The results were obtained from absolute ion-yield measurements using the SOLEIL synchrotron radiation facility for spectral bandpasses of 65 meV or 250 meV. In the photon energy region 398–403 eV, 1s⟶2p autoionizing resonance states dominated the cross section spectrum. Analyses of the experimental profiles yielded resonance strengths and Auger widths. In the 415–440 eV photon region 1s⟶(1s2s22p2 4P)np and 1s⟶(1s2s22p2 2P)np resonances forming well-developed Rydberg series up n=7 and n=8 , respectively, were identified in both the single and double ionization spectra. Theoretical photoionization cross-section calculations, performed using the R-matrix plus pseudo-states (RMPS) method and the multiconfiguration Dirac-Fock (MCDF) approach were bench marked against these high-resolution experimental results. Comparison of the state-of-the-art theoretical work with the experimental studies allowed the identification of new resonance features. Resonance strengths, energies and Auger widths (where available) are compared quantitatively with the theoretical values. Contributions from excited metastable states of the N+ ions were carefully considered throughout.

Download Full-text

High-resolution photoabsorption cross-section measurements of SO2at 198 K from 213 to 325 nm

Journal of Geophysical Research Atmospheres ◽

10.1029/2010je003707 ◽

2011 ◽

Vol 116 (E3) ◽

Cited By ~ 13

Author(s):

D. Blackie ◽

R. Blackwell-Whitehead ◽

G. Stark ◽

J. C. Pickering ◽

P. L. Smith ◽

...

Keyword(s):

High Resolution ◽

Cross Section ◽

Photoabsorption Cross Section

Download Full-text

High Resolution Imaging Forty Years Ago

Symposium - International Astronomical Union ◽

10.1017/s0074180900107855 ◽

1994 ◽

Vol 158 ◽

pp. 337-341

Author(s):

R. C. Jennison

Keyword(s):

High Resolution ◽

Point Sources ◽

Resolving Power ◽

High Angular Resolution ◽

Electromagnetic Spectrum ◽

High Resolution Imaging ◽

Resolution Imaging ◽

Optical Telescopes ◽

Very High ◽

Better Than

This conference is concerned with the very high resolution imaging of cosmic sources in many parts of the electromagnetic spectrum. Various techniques are now available and the equipment is often automated and highly sophisticated but the term ‘very high angular resolution’ is comparative. Many of the problems existed over forty years ago when the best resolving power was about half a degree and the two major radio ‘stars’ appeared to be point sources. Very high resolution imaging in those days was the struggle to reach one minute of arc and Hanbury Brown had set his sights on considerably better than one second of arc with the concept of the intensity interferometer. The dream was to achieve a resolving power comparable to that of optical telescopes.

Download Full-text

Photoabsorption cross section of C70 thin films from visible to vacuum ultraviolet

The Journal of Chemical Physics ◽

10.1063/1.3153275 ◽

2009 ◽

Vol 130 (23) ◽

pp. 234510 ◽

Cited By ~ 5

Author(s):

H. Yagi ◽

K. Nakajima ◽

K. R. Koswattage ◽

K. Nakagawa ◽

H. Katayanagi ◽

...

Keyword(s):

Thin Films ◽

Cross Section ◽

Vacuum Ultraviolet ◽

Photoabsorption Cross Section

Download Full-text

High-resolution photoabsorption cross-section measurements of SO2at 160 K between 199 and 220 nm

Journal of Geophysical Research Atmospheres ◽

10.1029/2008je003319 ◽

2009 ◽

Vol 114 (E6) ◽

Cited By ~ 17

Author(s):

J. Rufus ◽

G. Stark ◽

A. P. Thorne ◽

J. C. Pickering ◽

R. J. Blackwell-Whitehead ◽

...

Keyword(s):

High Resolution ◽

Cross Section ◽

Photoabsorption Cross Section

Download Full-text

The spherical Fabry—Perot interferometer as an instrument of high resolving power for use with external or with internal atomic beams

Proceedings of the Royal Society of London Series A - Mathematical and Physical Sciences ◽

10.1098/rspa.1961.0161 ◽

1961 ◽

Vol 263 (1314) ◽

pp. 289-308 ◽

Cited By ~ 34

Keyword(s):

High Resolution ◽

Hyperfine Structure ◽

Atomic Beam ◽

Resonance Line ◽

Resolving Power ◽

Light Power ◽

Line Structure ◽

Fabry Perot ◽

Atomic Beams ◽

Very High

The spherical Fabry -Perot interferometer was designed by P. Connes as an instrument capable of realizing higher resolving power than the normal Fabry -Perot interferometer, by virtue of its greater light power at high resolution, and the much lower requirement with regard to accuracy of adjustment. The instrument has now been used successfully in the resolution of structure in the resonance line of the arc spectrum of barium; components with a separation of 2.0x 10 -3 cm -1 have been resolved; they were observed in the absorption produced by a Jackson -Kuhn atomic beam, of high collimation. The instrument has also been used for observing line structure with an absorbing atomic beam traversing the interior of the interferometer; by this means the amount of material required for observing hyperfine structure using an atomic beam , even with very high collimation, can be reduced to a few milligrams, or approximately 100 times less than that required with an atomic beam external to the interferometer, so that enriched isotopes, available in small quantities, can be used; alternatively, adequate absorption can be obtained with much higher collimations of the beam, and correspondingly improved limits of resolution.

Download Full-text

High-resolution photoabsorption cross-section measurements of SO2at 295 K between 198 and 220 nm

Journal of Geophysical Research Atmospheres ◽

10.1029/1999je001022 ◽

1999 ◽

Vol 104 (E7) ◽

pp. 16585-16590 ◽

Cited By ~ 40

Author(s):

G. Stark ◽

Peter L. Smith ◽

J. Rufus ◽

A. P. Thorne ◽

J. C. Pickering ◽

...

Keyword(s):

High Resolution ◽

Cross Section ◽

Photoabsorption Cross Section

Download Full-text

Photoionization Cross Sections of Carbon-Like N+ near the K-Edge (390 eV - 440 eV)

10.20944/preprints202104.0142.v1 ◽

2021 ◽

Author(s):

Jean-Paul Mosnier ◽

Eugene T Kennedy ◽

Jean-Marc Bizau ◽

Denis Cubaynes ◽

Ségolène Guilbaud ◽

...

Keyword(s):

High Resolution ◽

Cross Section ◽

Cross Sections ◽

Experimental Studies ◽

Photoionization Cross Section ◽

Theoretical Work ◽

Rydberg Series ◽

R Matrix ◽

Resonance Strengths ◽

Nitrogen Ion

High-resolution K-shell photoionization cross-sections for the C-like atomic nitrogen ion (N+) are reported in the 398 eV (31.15 Å) to 450 eV (27.55 Å) energy (wavelength) range. The results were obtained from absolute ion-yield measurements using the SOLEIL synchrotron radiation facility for spectral bandpasses of 65 meV or 250 meV. In the photon energy region 398 eV - 403 eV, 1s⟶2p autoionizing resonance states dominated the cross section spectrum. Analyses of the experimental profiles yielded resonance strengths and Auger widths. In the 415 eV - 440 eV photon region 1s⟶1s2s22p2 4Pnp and 1s⟶1s2s22p2 2Pnp resonances forming well-developed Rydberg series up n=7 and n=8 , respectively, were identified in both the single and double ionization spectra. Theoretical photoionization cross-section calculations, performed using the R-matrix plus pseudo-states (RMPS) method and the multiconfiguration Dirac-Fock (MCDF) approach were bench marked against these high-resolution experimental results. Comparison of the state-of-the-art theoretical work with the experimental studies allowed the identification of new resonance features. Resonance strengths, energies and Auger widths (where available) are compared quantitatively with the theoretical values. Contributions from excited metastable states of the N+ ions were carefully considered throughout.

Download Full-text

High Resolution Scanning Microscopy—What Next?

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100113718 ◽

1975 ◽

Vol 33 ◽

pp. 18-19

Author(s):

A. V. Crewe

Keyword(s):

High Resolution ◽

Phase Contrast ◽

Scanning Microscopy ◽

Resolving Power ◽

Current Status ◽

Scanning Microscope ◽

Conventional Microscope ◽

The One ◽

Very High

The current status of high resolution scanning microscopy is probably well enough known that it needs little elaboration. Perhaps it is sufficient to say that resolving power can be achieved which is equal to that of the conventional microscope, that contrast is very high, and that a variety of forms of contrast are available which make use of both elastic and inelastically scattered electrons. The one weakness of the scanning microscope of which we are aware is that it is not as efficient as the conventional microscope for phase contrast or obtaining diffraction information.

Download Full-text