Spectroscopy collinear

These limitations have recently been eliminated using solid-state sources of femtosecond pulses. Most of the femtosecond dye laser teclmology that was in wide use in the late 1980s [11] has been rendered obsolete by tliree teclmical developments the self-mode-locked Ti-sapphire oscillator [23, 24, 25, 26 and 27], the chirped-pulse, solid-state amplifier (CPA) [28, 29, 30 and 31], and the non-collinearly pumped optical parametric amplifier (OPA) [32, 33 and 34]- Moreover, although a number of investigators still construct home-built systems with narrowly chosen capabilities, it is now possible to obtain versatile, nearly state-of-the-art apparatus of the type described below Ifom commercial sources. Just as home-built NMR spectrometers capable of multidimensional or solid-state spectroscopies were still being home built in the late 1970s and now are almost exclusively based on commercially prepared apparatus, it is reasonable to expect that ultrafast spectroscopy in the next decade will be conducted almost exclusively with apparatus ifom conmiercial sources based around entirely solid-state systems. 

Eqnation (B3.4.1) is general and applies to both scattering and bonnd state spectroscopy. Scattering will be considered first. For shnplicity, the discnssion rises the collinear model for the A -l- BC AB -l- C reaction (i.e. assuming all particles lie on a line). This model is easy to visualize and embodies most elements of tlnee-dimensional (3D) scattering of larger molecules. 

The experimental configuration of the pump-probe experiment is similar to Ref. [5]. A home built non-collinear optical parametric amplifier (nc-OPA) was used as a pump, providing Fourier-transform-limited 30 fs pulses, which could be spectrally tuned between 480-560 nm. In all experiments white-light generated in a sapphire crystal using part of the fundamental laser (800 nm), was used as probe light. In the pump-probe experiments the pump was tuned to the S2 0-0 band for carotenoids with n>l 1. In the case of M9, it was not possible to tune the nc-OPA to its 0-0 transition, and hence another nc-OPA tuned to 900 nm was frequency doubled and used for excitation. In addition to conventional transient absorption pump-probe measurements, we introduce pump-deplete-probe spectroscopy, which is sensitive to the function of an absorbing state within the deactivation network. In this technique, we... 

Hyperfine structure measurements using on-line atomic-beam techniques are of great importance in the systematic study of spins and moments of nuclei far from beta-stability. We will discuss the atomic-beam magnetic resonance (ABMR) method, and laser spectroscopy methods based on crossed-beam geometry with a collimated thermal atomic-beam and collinear geometry with a fast atomic-beam. Selected results from the extensive measurements at the ISOLDE facility at CERN will be presented. 

As discussed in the preceeding section, an extensive investigation of the rare-earth region is being performed by collinear laser spectroscopy. It includes a two-dimensional mapping of the (N, Z)-plane, covering not only scattered isotopic sequences but isotopes of a range of elements. 

As mentioned above, the radon and radium sequences have been investigated by collinear fast-beam laser spectroscopy, whereas in francium all three atomic-beam methods, ABMR, atomic-beam laser spectroscopy and collinear laser spectroscopy, have contributed. 

Prior to about 1955 much of the nuclear information was obtained from application of atomic physics. The nuclear spin, nuclear magnetic and electric moments and changes in mean-squared charge radii are derived from measurement of the atomic hyperfine structure (hfs) and Isotope Shift (IS) and are obtained in a nuclear model independent way. With the development of the tunable dye laser and its use with the online isotope separator this field has been rejuvenated. The scheme of collinear laser/fast-beam spectroscopy [KAU76] promised to be useful for a wide variety of elements, thus UNISOR began in 1980 to develop this type of facility. The present paper describes some of the first results from the UNISOR laser facility. 

Several groups at ISOLDE are planning further improvements of their techniques. For each element the most appropriate experimental scheme has to be found. Today, collinear laser spectroscopy is the most general high-resolution and sensitive method for optical spectroscopy on radioactive beams delivered by on-line mass separators. Its sensitivity ranges from 10 - 10 atoms/s depending on the strength and multiplicity of the optical transitions. 

COLLINEAR SPECTROSCOPY IN FAST ATOMIC AND IONIC BEAMS ... 

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 schematic view of the Mainz apparatus for collinear laser spectroscopy, installed at Isolde is given in fig 4. The 60 keV ion beam is set collinear with the laser beam, then accelerated (or decelerated) and finally neutralized in charge exchange cell. By Doppler tuning the atomic absorption is set resonnant with the stabilized laser frequency, and the fluorescence emitted is detected. 

In order to improve the signal-to-noise ratio in collinear laser spectroscopy, an ion source with bunched beam release was tested successfully. For this purpose, the temperature of a cold trap" inside the ion source is reduced for storage of reaction products, which are released from the trap during a subsequent period of increased temperature. The release of indium was found to occur with a FWHM of approximately 0.5s, corresponding to a... 

J. Eberz et al., "Collinear Laser Spectroscopy on l08fr)108mIn Using an Ion Source with Bunched Beam Release", to be published. 

Sundberg, R.L., Imre, D., Hale, M.O., Kinsey, J.L., and Coalson, R.D. (1986). Emission spectroscopy of photodissociating molecules A collinear model for CH3I and CD3I, J. Phys. Chem. 90, 5001-5009. 

Fig. 12. Radiofrequency and gradient pulse sequence for velocity exchange spectroscopy (VEXSY) in which successive PGSE pulse pairs (G, and G2X separated by a delay time t , are applied. For an unambiguous correlation, Gj and Gj are required to be collinear. Note the two orthogonal Fourier domains represented (schematically) by r, and tj- Fourier transformation with respect to the acquisition time leads to a third spectral dimension.

Monz, L., Hohmann, R., Kluge, H.-J., Kunze, S., Lantzsch, J., Otteu, E.W., Passler, G., Senne, P., Stenner, J., Stratmann, K., Wendt, K. and Zimmer, K., Fast, low-level detection of strontium-90 and strontium-89 in environmental samples by collinear resonance ionisation spectroscopy. Spectrochim. Acta, 488 (1993) 1655-1671. 

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