Isotope excitation

Nuclear decay processes that are often used to populate Mossbauer isotope excited states are (30) electron capture (electron + proton neutron), / decay (neutron - proton + electron), and isomeric transition (a long half-life nuclear excited state decays to the Mossbauer excited state). In addition, several of the parent nuclides of the heavy isotopes can be populated by a-particle emission. 

It is obvious that the absorbed energy in a given frequency region will have a finite value only if the emission and absorption contours have finite values in this region. For example, the conditions represented in Figure II would correspond to the. requirements for excitation of a single isotopic species, whereas in Figure 4, both mono- and di-isotopic excitations are indicated. 

Several years ago, there was a lot of excitement concerning a method of using lasers to separate isotopes. A laser was adjusted to a very narrow wavelength that would excite only one of the uranium isotopes. With only one isotope excited it was projected that a near single stage separation method was possible. Little has been said about this method in recent years. The lack of the need for uranium separation has placed a damper on the developments. 

Principles and Characteristics In Chp. 8 of ref. [113a] we discussed elemental analysis modes in which the sample was approached to the elemental analysis tool. Mobile spectrometers are more suitable for in situ or on-line monitoring. Various such tools have recently been developed, as portable XRF and LIES A . X-ray fluorescence (XRF) analysis may be based on either electron or radio-isotope excitation. Compact, rugged, and reliable on-line XRF analysers based on radioisotope excitation have been described [25]. On-line (micro-)XRF analysers need very little if any sample preparation compared to many other techniques. Of prime importance is that the surface at the cell window represents the whole sample stream. The instruments are capable of excellent on-line performance for many applications such as process liquids, slurries, solids (e.g., polymer pellets), powders, and others. Process control XRF allows simultaneous determination of up to 32 elements. 

Due to the very high intensity of the laser beams and their coherent nature they may be used in a variety of ways where controlled energy is required. Lasers are used commercially for excitation with a specific energy, e.g. in Raman spectroscopy or isotope separation. 

Early laser Isotope separation after IR multiphoton excitation high selectivity at room temperature... 

We further make the following tentative conjecture (probably valid only under restricted circumstances, e.g., minimal coupling between degrees of freedom) In quantum field theories, too, the YM residual fields, A and F, arise because the particle states are truncated (e.g., the proton-neutron multiplet is an isotopic doublet, without consideration of excited states). Then, it is within the truncated set that the residual fields reinstate the neglected part of the interaction. If all states were considered, then eigenstates of the form shown in Eq. (90) would be exact and there would be no need for the residual interaction negotiated by A and F. 

This is the basic process in an inductively coupled plasma discharge (ICP). The excited ions can be examined by observing the emitted light or by mass spectrometry. Since the molecules have been broken down into their constituent atoms (as ions) including isotopes, these can be identified and quantified by mass spectrometry, as happens with isotope ratio measurements. 

Although protons and neutrons are not emitted from the ground states of these isotopes, there are many cases where particles are emitted from excited states. For example, Cs decays by electron capture and -emission to excited levels ia and ia 7% of these cases protons are emitted from... 

The cross-section curve a(E) gives the dependence of the nuclear cross-section on the projectile energy, E. The measured energy spectra of emitted particles or the excitation curve N(Eq) wiU depend on the depth profile N(x) of the analyzed isotope and on the cross-section curve (t(E(x)), where E(x) gives the energy of the projectiles at a depth x. Evaluation of the depth profile N (x) from measured energy spectra or excitation curves often requires a tedious evaluation procedure if the cross-section curve has a complex structure. It is simplified for two special types of behavior of the cross-section curve ... 

When, in NRA, resonances are used, and the depth profile of an isotope A is obtained from the excitation curve N(Eq), the reaction depth x is given by the requirement that projectiles incident with energy Eq are slowed down to the resonance energy Fr at X, which leads to ... 

In the early years of this century the periodic table ended with element 92 but, with J. Chadwick s discovery of the neutron in 1932 and the realization that neutron-capture by a heavy atom is frequently followed by j6 emission yielding the next higher element, the synthesis of new elements became an exciting possibility. E. Fermi and others were quick to attempt the synthesis of element 93 by neutron bombardment of but it gradually became evident that the main result of the process was not the production of element 93 but nuclear fission, which produces lighter elements. However, in 1940, E. M. McMillan and P. H. Abelson in Berkeley, California, were able to identify, along with the fission products, a short-lived isotope of... 

Other reasons for investigating plutonium photochemistry in the mid-seventies included the widely known uranyl photochemistry and the similarities of the actinyl species, the exciting possibilities of isotope separation or enrichment, the potential for chemical separation or interference in separation processes for nuclear fuel reprocessing, the possible photoredox effects on plutonium in the environment, and the desire to expand the fundamental knowledge of plutonium chemistry. 

Z. Physik 126. 344 (1944) (change in value of isotope shift in atomic spectra) G. Scharff-Goldhaber, Phys. Rev. 90, 587 (1953) (excitation energy to first excited states of even-even nuclei). 

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