Atoms resonance ionization spectroscopy

Resonance ionization spectroscopy is a photophysical process in which one electron can be removed from each of the atoms of a selected type. Since the saturated RIS process can be carried out with a pulsed laser beam, the method has both time and space resolution along with excellent (spectroscopic) selectivity. In a recent article [2] we showed, for example, that all of the elements except helium, neon, argon, and fluorine can be detected with the RIS technique. However, with commercial lasers, improved in the last year, argon and fluorine can be added to the RIS periodic table (see figure 2). 

Resonant and non-resonant laser post-ionization of sputtered uranium atoms using SIRIS (sputtered initited resonance ionization spectroscopy) and SNMS (secondary neutral mass spectrometry) in one instrument for the characterization of sub-pm sized single microparticles was suggested by Erdmann et al.94 Resonant ionization mass spectrometry allows a selective and sensitive isotope analysis without isobaric interferences as demonstrated for the ultratrace analysis of plutonium from bulk samples.94 Unfortunately, no instrumental equipment combining both techniques is commercially available. 

Fig. 4 Right Principle of resonance ionization spectroscopy. Three tunable pulsed Dye lasers are used to stepwize excite and ionize the atom. The effective cross-sections are indicated for the different transitions in cm2. Left Layout of a laser ion source for on-line mass separators.

RESONANCE IONIZATION SPECTROSCOPY IN THERMAL ATOMIC BEAMS ... 

Graphite furnace AAS Atomic fluorescence spectroscopy Inductively-coupled-plasma optical-emission spectroscopy Glow-discharge optical-emission spectroscopy Laser-excited resonance ionization spectroscopy Laser-excited atomic-fluorescence spectroscopy Laser-induced-breakdown spectroscopy Laser-induced photocoustic spectroscopy Resonance-ionization spectroscopy... 

The previous experiments on ytterbium [50] have been extended using resonance ionization spectroscopy on a fast atomic ytterbium beam [71]. 

F. Vrehen, D. Polder, and H. M. Gibbs Applications of Resonance Ionization Spectroscopy in Atomic and Molecular Physics, M. 

In atomic laser spectroscopy, the laser radiation, which is tuned to a strong dipole transition of the atoms under investigation, penetrates the volume of species evaporated from the sample. The presence of analyte atoms can be measmed by means of the specific interaction between atoms and laser photons, such as by absorption techniques (laser atomic absorption spectrometry, LAAS), by fluorescence detection (laser-induced fluorescence spectroscopy, LIFS), or by means of ionization products (electrons or ions) of the selectively excited analyte atoms after an appropriate ionization process (Figures lA and IB). Ionization can be achieved in different ways (1) by interaction with an additional photon of the exciting laser or of a second laser (resonance ionization spectroscopy, RIS, or resonance ionization mass spectrometry, RIMS, respectively, if combined with a mass detection system) (2) by an electric field applied to the atomization volume (field-ionization laser spectroscopy, FILS) or (3) by collisional ionization by surrounding atoms (laser-enhanced ionization spectroscopy, LEIS). 

The ionization potential of an element is one of its fundamental properties. It is known that the first ionization potential of heavy elements depends on relativistic effects. The Mainz group, in Germany, systematically determined the first ionization potential of the actinide elements from Ac through Es using laser spectroscopy as shown in Table 18.12 (Becke et al. 2002). O Figure 18.24 shows the comparison of ionization potentials between lanthanide and actinide atoms (Moore 1971 Becke et al. 2002). The atomic level structure of Fm (2.7 x 10 ° atoms) with a half-life of 20.1 h was studied for the first time by the method of resonance ionization spectroscopy. Two atomic levels were identified at wave numbers (25,099.8 0.2) cm and (25,111.8 0.2) cm (Sewtz et al. 2003). 

Resonance Ionization Spectroscopy Inert Atom Detection... 

Resonance ionization spectroscopy (RIS) is based on resonance multistep excitation of high-lying levels of free analyte atoms and their subsequent ionization. Ionization may be caused by the photons of the final laser step (photoioniza-... 

As we have seen, collisions are important for the signal generation in LEI. In low-pressure experiments photoionization instead is the principal origin of the signal. The term Resonance Ionization Spectroscopy (RIS) is then frequently used. Several examples of opto-galvanic detection schemes for different atoms are shown in Fig.9.11. If multi-photon excitation of the atoms to be studied is used the technique is referred to as REMPI (REsonance Multi-Photon Ionization) spectroscopy. The selectivity of RIS and REMPI can be further enhanced by using a mass spectrometer to ana-... 

C.H. Chen, G.S. Hurst, M.G. Payne Resonance ionization spectroscopy Inert gas detection, in H.J. Beyer, H. Kleinpoppen (eds.) Progress in Atomic Spectroscopy Pt.C (Plenum, New York 1984) p. 115 ... 

Hurst, G. S., Nayfeh, M. H., and Young, J. P. (19776). One-atom detection using resonance ionization spectroscopy. Physical Review A, 15, 2283-2292. 

Also crucial to our experiment were recent advances in the techniques of optical spectroscopy[13]. We combine the pulsed Ps source with a high power narrowband dye laser[23] capable of partially saturating the highly forbidden two photon 1S-2S transition over a sizable volume of space, the use of two-photon techniques[24] that allow us to avoid the considerable first order Doppler width and to excite all the Ps when the laser is tuned to the atomic resonance, and a single atom, resonant ionization detector [25] with a low background counting rate and 40% quantum efficiency. 

The ionization energy Ej = 60160.1(4) cm-" (7.45896(5) eV) was derived from double-resonance ionization spectroscopy on a Rh atomic beam [5] while approximate values had been obtained Ej = 62000 cm from a two-member series [6], Ej=60197 cm by interpolation between data from spectra of neighboring elements [7], and Ej=60813 cm by electron-impact appearance potential measurements [8]. 

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