Isolated Building Blocks of Photonic Materials:  High-Resolution Spectroscopy of Excited States of Jet-Cooled Push-Pull Stilbenes

2002 ◽  
Vol 106 (11) ◽  
pp. 2446-2456 ◽  
Author(s):  
R. A. Rijkenberg ◽  
D. Bebelaar ◽  
W. J. Buma ◽  
J. W. Hofstraat
Keyword(s):  
High Resolution ◽  
Excited States ◽  
Building Blocks ◽  
High Resolution Spectroscopy ◽  
Photonic Materials

New applications of the genetic algorithm for the interpretation of high-resolution spectra

2004 ◽  
Vol 82 (6) ◽  
pp. 804-819 ◽  
Author(s):  
W Leo Meerts ◽  
Michael Schmitt ◽  
Gerrit C Groenenboom
Keyword(s):  
Genetic Algorithm ◽  
High Resolution ◽  
Van Der Waals ◽  
Computing Time ◽  
Zero Point ◽  
Building Blocks ◽  
Molecular Structures ◽  
High Resolution Spectroscopy ◽  
Van Der Waals Clusters ◽  
Point Energy

Rotationally resolved electronic spectroscopy yields a wealth of information on molecular structures in different electronic states. Unfortunately, for large molecules the spectra get rapidly very congested owing to close-lying vibronic bands, other isotopomers with similar zero-point energy shifts, or large-amplitude internal motions. A straightforward assignment of single rovibronic lines and, therefore, line position assigned fits are impossible. An alternative approach is unassigned fits of the spectra using genetic algorithms (GAs) with special cost functions for evaluation of the quality of the fit. This paper decribes the improvements we established on the GA method discussed before (J.A. Hageman, R. Wehrens, R. de Gelder, W.L. Meerts, and L.M.C. Buydens. J. Chem. Phys. 113, 7955 (2000)). In particular, we succeeded in obtaining a dramatic reduction in computing time that made it possible to apply the GA process in a large number of cases. A completely automated fit of a rotationally resolved laser-induced fluorescence spectrum without any prior knowledge of the molecular parameters can now be performed in less than 1 h. We demonstrate the power of the method on a number of typical examples such as very dense rovibronic spectra of van der Waals clusters and overlapping spectra due to different isotopomers. The discussed results demonstrate the extreme power of the GA in automated fitting and assigning of complex spectra. It opens the road to the analysis of complex spectra of biomolecules and their building blocks. Key words: high-resolution spectroscopy, genetic algorithm, biomolecules, structure, van der Waals clusters.

scholarly journals High resolution spectroscopy in the XUV with pairs of mutually coherent and time-delayed laser harmonics

2004 ◽  
Vol 22 (3) ◽  
pp. 199-202 ◽  
Author(s):  
MARCO BELLINI ◽  
STEFANO CAVALIERI ◽  
CHIARA CORSI ◽  
ROBERTO ERAMO ◽  
MARZIA MATERAZZI
Keyword(s):  
High Resolution ◽  
Excited States ◽  
Extreme Ultraviolet ◽  
Noble Gas ◽  
Laser Pulses ◽  
High Order ◽  
Atomic Spectroscopy ◽  
Intense Laser ◽  
High Resolution Spectroscopy ◽  
Intense Laser Pulses

We present a Ramsey technique using high-order harmonics for high-resolution atomic spectroscopy in the extreme ultraviolet. Pairs of time-delayed and phase-coherent harmonic pulses generated by the interaction of ultrashort and intense laser pulses with a noble gas are used to study excited states of krypton.

Excited states of polysilanes: High-resolution spectroscopy and molecular modeling

1991 ◽  
Vol 1 (3) ◽  
pp. 343-360 ◽  
Author(s):  
A. Tilgner ◽  
H. P. Trommsdorff ◽  
J. M. Zeigler ◽  
R. M. Hochstrasser
Keyword(s):  
Molecular Modeling ◽  
High Resolution ◽  
Excited States ◽  
High Resolution Spectroscopy

Microcalorimeters for X-Ray Spectroscopy

1988 ◽  
Vol 102 ◽  
pp. 41
Author(s):  
E. Silver ◽  
C. Hailey ◽  
S. Labov ◽  
N. Madden ◽  
D. Landis ◽  
...  
Keyword(s):  
High Resolution ◽  
High Efficiency ◽  
Thermal Response ◽  
Low Noise ◽  
High Resolution Spectroscopy ◽  
Superconducting Transition ◽  
Sapphire Substrates ◽  
Laboratory Plasmas ◽  
Adiabatic Demagnetization ◽  
Theoretical Predictions

The merits of microcalorimetry below 1°K for high resolution spectroscopy has become widely recognized on theoretical grounds. By combining the high efficiency, broadband spectral sensitivity of traditional photoelectric detectors with the high resolution capabilities characteristic of dispersive spectrometers, the microcalorimeter could potentially revolutionize spectroscopic measurements of astrophysical and laboratory plasmas. In actuality, however, the performance of prototype instruments has fallen short of theoretical predictions and practical detectors are still unavailable for use as laboratory and space-based instruments. These issues are currently being addressed by the new collaborative initiative between LLNL, LBL, U.C.I., U.C.B., and U.C.D.. Microcalorimeters of various types are being developed and tested at temperatures of 1.4, 0.3, and 0.1°K. These include monolithic devices made from NTD Germanium and composite configurations using sapphire substrates with temperature sensors fabricated from NTD Germanium, evaporative films of Germanium-Gold alloy, or material with superconducting transition edges. A new approache to low noise pulse counting electronics has been developed that allows the ultimate speed of the device to be determined solely by the detector thermal response and geometry. Our laboratory studies of the thermal and resistive properties of these and other candidate materials should enable us to characterize the pulse shape and subsequently predict the ultimate performance. We are building a compact adiabatic demagnetization refrigerator for conveniently reaching 0.1°K in the laboratory and for use in future satellite-borne missions. A description of this instrument together with results from our most recent experiments will be presented.

Sign in / Sign up

Export Citation Format

Share Document