Spectra emitted

Fig. 12.8 (a) The experimental setup, (b) Optical spectra emitted from a CBNL under different pump levels. Inset Integrated emitted power vs. pump power, showing laser threshold at 800 mW. Inset 2 Lasing pattern. Reprinted from Ref. 21 with permission. 2008 Institute of Electrical and Electronics Engineers... 

The number of lanthanide ions that can be studied simultaneously in the same aqueous solution is dependent on several considerations. Firstly, the extraction constants Ke of the lanthanides change by approximately 104 on transition from La3+ to Lu3+. It is thus difficult to provide a constant TTA concentration across the lanthanide series because of the inaccuracy of the D values. Secondly, the gamma ray spectra emitted by the tracers from each phase must contain one or more characteristic peaks which can be easily counted for a desired element. We must choose several lanthanide mixtures. 

The relative intensity of the 23.875-k.e.v. O line of the x-ray spectra emitted by the source depended on the chemical form of the... 

MR screens. In Picker Spectra screens and in the General Electric Co. Blue Max screens. At higher terbium concentrations, the emission spectra emit predominantly green at 542 nm with efficiencies of about 20% comparable to ZnCdS Ag phosphors (24). These green emitting phosphors are suitable for green sensitive films. 

In 1934 Mohorovicic proposed the existence of a bound state of a positron and an electron which, he (incorrectly) suggested, might be responsible for unexplained features in the spectra emitted by some stars. However, as summarized by Kragh (1990), Mohorovicic s ideas on the properties of this new atom were somewhat unconventional, and the name electrum which he gave to it did not become widespread but was later replaced by the present appellation, positronium (Ruark, 1945), with the chemical symbol Ps. 

Ever since the foundations of spectroscopy were laid the problem of the relationship between the optical spectra emitted or absorbed by matter and the microscopic properties of the matter has been regarded as a fundamental problem. A class of very interesting systems with this regard is provided by non-metallic compounds of rare-earth ions with partially filled 4f shells. Their rich electronic structure is only weakly perturbed by the environment and provides a detailed fingerprint of the surrounding arrangement of atoms and their interactions with the f-electrons. 

In Chapter 1, section 7, it was explained that very precise overlap of atomic absorption and emission profiles is required to obtain sensitive absorbance measurements. Absorption spectra of atoms at flame temperatures are much simpler than the emission spectra emitted by hollow cathode lamps. The possible transitions corresponding to electronic excitation of an atom may be shown as vertical lines on an energy level diagram, in which the vertical displacement... 

In order to better understand how our existing model of the atom evolved, we must step back to about 1900, when physicist Max Planck discovered an unusual property of atoms. While studying the spectra emitted from glowing objects, Planck concluded that energy could be emitted or absorbed from atoms only in fixed amounts, or quanta. He proposed that this amount of energy (E) was directly proportional to the frequency (v) of the electromagnetic wave. Mathematically, this is expressed in the formula ... 

Fine structures of photoelectron. Auger electron and X-ray spectra emitted from molecules through the transition from valence to inner-shells are sensitive to the change in chemical environments surrounding the atom of interest, and then have been used extensively for studies of electronic structures of chemical compounds[l-9]. For obtaining these spectra, photons, electrons and accelerated ions have been employed as excitation sources. However different kinds of excitation methods make explanations of the fine structures and/or satellite structures of Auger and X-ray spectra complicated. This is a main cause why intensity distributions of these spectra can not be discussed quantitatively. 

In photoelectron. Auger and X-ray spectroscopies, the frozen core and sudden approximations have frequently been used for their simplicity. However, interesting chemical bond effects in Auger and X-ray spectra have not yet been explained by such over simplified approximations. The representatives are remarkable changes in satellite intensity distributions appeared in X-ray and Auger spectra emitted from a series of fluorides [14-20], Introduction of a new concept of... 

TABLE 2. Observed and calculated difference energies of the satellite lines (XI) and diagram lines (XO) in F Ka fluorescent X-ray spectra emitted from alkali metal... 

As can be seen from Fig. 10, the Auger M line intensity becomes, through the mode 32, large for large ROR probability or for small AE defined in Fig. 2. This leads, in the first approximation, to reduction in the fluorescence yield Yxi and then also reduction in the intensity ratio of Xl/XO as shown in Fig. 11, though the fluorescence yield is, strictly speaking, a function both of Auger and X-ray yields. Thus chemical bond effects in the satellite intensities of the XI lines in the F Ka fluorescent X-ray spectra emitted from the alkali-metal fluorides have now successfully been explained. 

An inner-shell electron can be excited by photoabsorption to a bound state below the ionization threshold. From such an excited state Auger electrons are also emitted. This makes the structure of Auger spectra simple because the spectra are free from the shake-off peak due to multiple ionization. Aksela et al. [26] have studied F KVV Auger spectra emitted from a series of fluorides by use of the synchrotron radiation. Spectra taken from LiF and KF are shown in Figs. 14 16 as typical examples. 

Table 16.3 Spectra Emitted in Argon Plasma Jet with Addition of Reactive Gases...

Spectroscopy is the analysis of the characteristic spectra emitted by matter. Spectroscopists perform chemical analyses as part of many research laboratory projects, for quality control in industrial settings, and as part of forensics investigations for law enforcement agencies. 

Typical photon induced X-ray spectra, emitted from NaF, KF, RbF and CsF, are shown in Fig.l3. The intensity distributions of these spectra can be explained by taking only the shake and ROR processes into account, because they are free from the satellite X-rays emitted through the direct Coulomb ionization. Then photon induced satellite spectra can be used, in the following manner, to estimate the ion-induced or particle induced X-ray satellite intensities without any complicated calculations. This is because the excitation process in particle induced X-ray emission (PIXE) can be described by a snperposition of the direct Coulomb, the shake and ROR processes. Here the shake and ROR processes are common to both photon- and particle- induced X-ray emission spectra, allowing utilization of the same ROR probability to explain both spectra. 

Table 3 Spectra emitted in argon plasma jet with addition of reactive gases...

Emission spectra. Continuous or line spectra emitted by substances. (7.3) Empirical formula. An expression showing the types of elements present and... 

Optical emission spectrometry (OES) is based on the production and detection of line spectra emitted during the de-excitation of electrons in an atom when they fall from upper excited energy levels to lower energy levels. The affected electrons are outer electrons. 

Fig. 11.6 Polychromatic excitation spectra emitted by a Rh X-ray tube operated at various accelerating voltages. The excitation spectrum consists of a faremsstraWung continuum upon which the characteristic lines of the anode material are superimposed (adapted from [12]).

I. 24/V (kV) where E is the maximum energy of the impinging electrons and V the potential used to accelerate them. The continuum distribution reaches a maximum at 1.5 2 X so that an increase in the accelerating potential V causes a shift of the continuum towards shorter wavelengths. In Fig. 11.6 bremsstrahlung spectra emitted by X-ray tubes operated at different accelerating potentials are shown. 

Fig. 6.14 Microring laser device (a) and spectra emitted at excitation light intensities below (b) and above (c) the threshold intensity. Active material ...

Studies based on the observation of i.r. chemiluminescence from reactions where the reagents are prepared as uncollimated beams or molecular sprays have provided most of the little available information about how selective excitation of the reactants alters the specificity of energy disposal. In experiments in Polanyi s laboratory the spectra emitted by the reaction products are observed as a... 

Disregarding higher-order reflections only one value of the angle of deflection exists for a given wavelength. The spectra emitted by an element consist of a small number of characteristic lines. If the ionization of the element to be determined takes place in the K shell of the atom, it is mainly the K- (X line that is produced. The K- a line is always accompanied by the weaker K-B line. 

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