Beam foil

Utilization of data obtained from various plasma sources (e.g. beam-foil, tokamak and laser-produced plasma [287]) enabled the identification with high accuracy of the lines of highly ionized atoms in solar spectra. A special commision No 14 on Atomic and Molecular Data of the International Astronomical Union coordinates the activity on systematization of spectroscopic data, informs the astrophysics community on new developments and provides assessments and recommendations. It also provides reports which highlight these new developments and list all important recent literature references on atomic spectra and wavelength standards, energy level analyses, line classifications, compilations of laboratory data, databases and bibliographies. 

Lombardi, M. (1976). Alignment and orientation production measurement and conversion. In Beam Foil Spectroscopy, eds. I.A. 

Quantum beats have been observed in a variety of experiments, particularly in beam—foil measurements. Teubner et al. (1981) were the first to observe quantum beats in electron—photon coincidence measurements, using sodium as a target. The zero-field quantum beats observed by them are due to the hyperfine structure associated with the 3 Pii2 excited state (see fig. 2.20). The coincidence decay curve showed a beat pattern... 

Metastable muonium atoms in the 2s state have been produced with a beam foil technique at LAMPF and at the Tri University Meson Physics Facility (TRI-UMF) at Vancouver, Canada. Only moderate numbers of atoms could be obtained. The velocity resonance nature of the electron transfer reaction results in a muonium beam at keV energies. Very difficult and challenging experiments using electromagnetic transitions in excited states, particularly the 2 Si/2 2 Pi/2 classical Lamb shift and 2 Si/2-2 P3/2 splitting could be induced with microwaves. However, the achieved experimental accuracy at the 1.5 % level [18,19,20], does not represent a severe test of theory yet. 

In the early 1970s, when it had been recognized that experiments of beam-foil specfroscopy could produce lifetimes for many types of atomic transitions, we carried out a number of computations and analyses of transifion probabilities in atoms, with and without heavy valence-Rydberg state mixing. As we wrote in Ref. [26b], fhaf work revealed that (non int) corresponds to correlation vectors with small coefficients which are reasonably well decoupled from T and (int). This implies A) Their direct contribution to (, D /) is very small. I.e., the last three terms of eq. (12) are negligible because of the small... 

Beam-Foil Spectroscopy ed. by S. Bashkin (1976) Approx. 500 pages Price approx. DM 69.--... 

B II, actually originates from the B I quartet system. In this context, we may ask about the correct identification of the 2s2p P - 2s3s S transition in B II. Bashkin e( al. [17] have tentatively proposed a revised energy value for the S level, but other assignments may also be possible. Additional studies of the unpublished beam-foil material [19] might here provide a conclusive answer. 

Figure 1 shows that 8 terms of the B I quartet system are experimentally established, by means of absorption spectroscopy [8]. However, in emission spectra, studied by the beam-foil method, transitions between only 4 of these term have been reported. We now plan such measurements at higher resolution which should allow the separation of the quartet lines and those belonging to e.g. the B I doublet system or B III. Note also that only a theoretical value exists for the energy of the 2s2p3p "P term (dotted line in Fig. 1). Combinations between this even term and the adjacent odd-parity ones, 2s2p3s P and 2s2p3d P or should lie in the infrared region. Although this region has been studied in the region 1 - 4 pm [28] no quartet transitions seem to have been observed.

Other Techniques. There exist other areas of potential application of ion beams. Ion beams can excite transitions in outer electron shells, with information in the optical wavelengths. Beam foil spectroscopy has used such methods for years, but no regular analytical use has been made. Nevertheless, samples irradiated under ion bombardment glow with characteristic radiation visible to the eye or television camera. Certain chemical or physical properties could be inferred by analyzing this radiation, perhaps including the physical condition of carbon atoms in graphitic or organic states. Certainly opportunities exist. 

C.A. Nicolaides, D.R. Beck, On the possibility of observing nonexponential decay in autoionizing states. In Beam-Foil Spectroscopy, I. SelHn, D. Pegg, (Eds.), Plenum Press, New York, 1976, p. 77. 

T. Aberg and O. Goscinski Information Theoretical Interpretation of Level Populations and Charge Distribution in Beam Foil Spectroscopy Phys. Rev. A,2 24, 801 (1981). 

H.J. Andra, Fine structure, hyperfine structure tmd Lamb-shift measurements by the beam foil technique. Phys. Scr. 9,257 (1974)... 

Lifetime measurements where the conventional beam-foil is replaced by laser excitation are discussed by H. J. Andra (Part B, Chapter 20). 

In the helium sequence (N = 2) theoretical calculations have reached a very high accuracy, and the aim of recent beam-foil observations of highly charged heliumlike ions has mainly been to determine QED effects from the difference between measured and calculated level intervals. 

Since the photoabsorption measurements of Madden and Codling autoionization processes have been investigated by various methods. Excita-tion has been initiated by electrons, " by heavy particles, or by beam-foil interaction. Whereas the number of states that can be excited by photon impact is limited by selection rules, this limitation is less stringent for electron collisions, especially at low impact energies. For ion-atom or atom-atom collisions it is possible to provoke or suppress the excitation of certain types of autoionization states by careful selection of the collision partners. ... 

There is a strong analogy between these interference structures and the so-called quantum beats that are observed in photon emission studies when atoms are coherently excited into different states by beam-foil, laser excitation, or other methods. Both phenomena are due to time-dependent interferences of transitions from different states. In quantum-beat studies... 

Also the autoionizing states of alkali atoms were studied by the various methods in the last years. Ross and co-workers performed a systematic study of all alkali atoms, in which alkali vapor was bombarded with electrons at various energies and the ejected electrons were analyzed. But also other methods such as light absorption from ground-state or excited state" atoms, heavy particle collisions, " and beam-foil excitation were used to excite the autoionizing states. 

Fast-Beam (Beam-Foil) Spectroscopy H. J. Andrd... 

In principle there are two techniques to process porous substrates with thermoforming. A novel method was shown by Giselbrecht et at [23], who processed pre-ion-beamed foils with thermoforming. Later the formed structures were etched to achieve porous microstructures. The advantage of this method is the easy process setup. 

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