Spectroscopy high-resolution with lasers

In order to clarify the vibrational dynamics on the PES of the E+ electronic state of OCS, we attempted to record a high-resolution lE+-lE+ absorption profile of OCS free from the inhomogeneous broadening by introducing a technique of PHOFEX spectroscopy with a tunable high-resolution VUV laser light source [7, 9, 10]. 

When working on line with a mass separator, such as Isolde, the collinear laser spectroscopy is a method fully adapted. In a collaboration Orsay - Mainz, the second members of the principal series in francium have been located and studied at high resolution with this method. In table 1 the measured wavenumbers of the four lines are given. 

The main significance of the work so far carried out at Oxford is that it demonstrates the feasibility of making measurements of the IS - 2S transition with a frequency doubled cw system. This opens the way to considerable improvements in precision, but the interpretation of the measurements will depend on what other information is available - the transition frequency is sensitive to QED effects, the proton size, and the values of fundamental constants. Cynics might point out that after well over a decade of work on the IS - 2S transition, the results have produced no real surprises. A more optimistic view is that it is only over the last year or two that it has become possible to study the transition with the standard techniques of high resolution cw laser spectroscopy, and the next decade will bring dramatic developments. We shall see. 

Ludin AI, Lehmann BE (1995) High-resolution diode-laser spectroscopy on a fast beam of metastable atoms for detecting very rare krypton isotopes. Appl Phys B61 461-465 Maloszewski P, Zuber A (1982) Determining the turnover time of ground water systems with the aid of environmental tracers, I. Models and their apphcability. J Hydrol 57 207-231... 

NH Rich, HL Welsh. High-resolution Raman spectroscopy of gases with laser excitation. J Opt Soc Am 61 977-978, 1971. 

Figure 5.17 shows the rotational Raman spectrum of N2 obtained with 476.5 nm radiation from an argon ion laser. From this spectrum a very accurate value for Bq of 1.857 672 0.000 027 cm has been obtained from which a value for the bond length tq of 1.099 985 0.000 010 A results. Such accuracy is typical of high-resolution rotational Raman spectroscopy. 

Dye lasers have been one of the most widely used types of tunable laser. In pulsed conditions, typical peak powers are in the range of 10 -10 W. In the cw regime, reported powers are in the order of watts, with linewidths of around 1 MHz. Due to their flexibility in design and performance, dye lasers have been commonly used in a great variety of spectroscopic techniques, including high-resolution spectroscopy. 

Section IV explains a new approach to high resolution spectroscopy based on various kinds of saturation effects. Some of the experiments are performed inside the laser resonator, which implies the presence of coupling phenomena between the absorbing molecules under investigation and the laser oscillation itself. These feedback effects can be used for high-precision frequency stabilization and to measure frequency shifts and line profiles with an accuracy never... 

With the development of more versatile tunable semiconductor lasers in the near infrared, high-resolution absorption spectroscopy in this spectral range has been greatly improved. Magnetic field tuned semiconductor lasers as well as current tunable devices have been used. 

High-resolution Raman spectroscopy of gases with different He-Ne and Ar laser lines was also performed by Weber etal. The authors determined relative scattering cross-sections for the pure rotational Raman spectrum of Oj. 

A recently developed field of research is matrix isolation laser Raman spectroscopy 214a)-d) which allows the study of vibrational Raman spectra with high resolution. Even small isotopic frequency shifts or the influence of crystal structure on the vibrational frequencies may be determined with high precision. This provides an effective constraint on intermolecular forcefields. 

Gorlich, P., Moenke-Blankenburg, L. Laser in Spektro-metrie. Exp. Techn. d. Physik, Vol. XVII, pp. 105 ff. 1969. - Demtroder, W. High resolution spectroscopy with lasers. Phys. Rep. 7e, 5 (1973). - Arrecchi, F. T., Schulz-Dubois, E. O. Laser handbook, part II. Amsterdam North Holl. Publ. Comp. 1972. 

Although exceedingly useful, the application of OS is not without problems. Optical spectra in condensed media consist of broad bands without identifying features structural information can be derived by comparison with known species, or by high-resolution laser spectroscopy. The TR-OS is often limited to wavelengths >300 nm, excluding some prototypes of the most interesting species. 

Contents Spectroscopy with Lasers Introduction. Characteristic Features of Lasers as Spectroscopic light Sources. Spectroscopic Applications of Lasers. High-Resolution Spectroscopy Based on Saturation Effects. Spectroscopy of Laser Media. Conclusion. Zusammen-fassung. (418 references). 

Different schemes and recent results for high-resolution rotational coherence spectroscopy with picosecond and femtosecond laser pulses... 

After the introduction of frequency resolved CARS by Maker and Terhune [1], time resolved experiments became possible with the invention of high power lasers with femtosecond resolution. Leonhardt [2] and for example Hayden [3] performed femtosecond CARS experiments in liquids. A first femtosecond time resolved CARS experiment in gas phase was performed by Motzkus et. al. [4] where the wave packet dynamics of the dissociation of Nal was monitored. The first observation of wave packet dynamics in gaseous iodine was reported by Schmitt et al. [5]. They were able to observe dynamics in both, the ground and excited state with the same experiment. A summary of high resolution spectroscopy in gas phase by nonlinear methods is given by Lang et al. [6]. 

DilTcrcm schemes and recent results for high-resolution rotational coherence spectroscopy with picosecond and femtosecond laser pulses C. Kiehn, V.-V Matylitsky. A. Weiehert, M.-F. Gclin. W. Jar/eba and B Brutschy 73... 

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