Satellites, X-ray

In addition to primary features from copper in Eig. 2.7 are small photoelectron peaks at 955 and 1204 eV kinetic energies, arising from the oxygen and carbon Is levels, respectively, because of the presence of some contamination on the surface. Secondary features are X-ray satellite and ghost lines, surface and bulk plasmon energy loss features, shake-up lines, multiplet splitting, shake-off lines, and asymmetries because of asymmetric core levels [2.6]. 

Since the K radiation emitted from a magnesium anode consists of the intense Kbinding energies by 8.0 and 10.2 eV [20]. The satellites excited by the Kas and K<,6 lines are usually too weak to be observed. Similar features can be observed in XPS spectra excited using Ko, X-rays from aluminum. 

The line width of the X-ray source is on the order of 1 eV for A1 or Mg Ka sources but can be reduced to better than about 0.3 eV with the use of a monochromator. A monochromator contains a quartz crystal which is positioned at the correct Bragg angle for A1 Ka radiation. The monochromator narrows this line significantly and focuses it onto the sample. It also cuts out all unwanted X-ray satellites and background radiation. An important advantage of using a monochromator is that heat and secondary electrons generated by the X-ray source cannot reach the sample. 

These results have motivated researchers to determine theoretically what information could be extracted from a future high spectral resolution X-ray satellite. For example, Ozel Psaltis (2003) show that if the redshift is estimated from the energy of minimum flux in the line (assuming the line is absorption-like), then substantial systematic errors are possible in the resulting inference of the compactness GM/Rc2 if the star rotates rapidly. Bhat-tacharyya, Miller, Lamb (2003, in preparation) have begun a systematic... 

Other constraints come from recent observations from X-ray satellites. Most robust seem the data from the low mass X-ray binary EXO 0478-676 obtained by Cottam et al. [37], From the redshifted absorption lines from ionized Fe and O a gravitational redshift z = 0.23 was deduced this gives rise to a mass-to-radius relation... 

An accurate measure of the radius and the mass of an individual neutron star will be of fundamental importance to discriminate between different models for the equation of state of dense hadronic matter. Unfortunately such a crucial information is still not available. A decisive step in such a direction has been done thanks to the instruments on board of the last generation of X-ray satellites. These are providing a large amount of fresh and accurate observational data, which are giving us the possibility to extract very tight constraints on the radius and the mass for some compact stars. 

Fig. 9. Survey spectrum of 600 eV of K.A1 (S04)2. The different features are clearly visible photoelectron lines resulting from various orbitals, energy loss tails and X-ray satellites (S). The expanded insert of the potassium-carbon region reveals the characteristic spin orbit splitting of the K2p-level. Mg Ka irradation, total observation time 30 min...

The ideal solution is therefore to combine X-ray and optical surveys as they provide complementary approaches (see for example Adami et al. 2000a or Donahue et al. 2001). Let us note that future SZ cluster surveys will similarly have to be completed with optical data. The need for such a combined approach has been understood since the 80s. This is illustrated by Fig. 1 that shows the parallel evolution of cluster publications using X-rays or optical data since 1980 (with the arrival of modern X-ray satellites as Einstein, Rosat, Chandra and XMM-Newton). 

Figure 5. XPS spectra of the Si2p region of a clean silicon surface (Si0) recorded by (b) grounding the sample, (a) applying 0 to -10V pulses at 0.1 Hz, (c) applying 0 to +10 V pulses at 0.1 Hz. The Si0 peak is twinned, because when pulsed the sample experiences the ground and the applied potential 50% at a time. Sat. refers to peaks of the Ka3 4 x-ray satellites.

The data were smoothed using a 15 point cubic-quartic Savitzky and Golay (1A) algorithm, the x-ray satellites and a Shirley background were subtracted using computer routines available in the Vacuum Generators data analysis software. Only the treated data are presented here. 

X-ray spectroscopy has also been applied to the interpretation of solar spectra, which are emitted by solar flares. Now stellar objects are under investigation by X-ray satellites such as Chandra and XMM. Whereas the present X-ray telescopes are medium resolution devices, the next generation (Constellation-X, XEUS) will provide sufficient spectral resolution for detailed analysis. The spectra from distant object usually suffer from low statistics solar flares have low emission time and the observation time of stellar objects is limited. In addition, the electron distribution is not Maxwellian, in general, and some of the spectral lines may be polarized. Therefore, verified theoretical data are of great importance to interpret solar and stellar spectra, where they provide the only source of information on the plasma state. 

Within the last 25 years of X-ray spectroscopy on fusion devices, the theory of He-like ions has been developed to an impressive precision. The spectra can be modeled with deviations not more than 10% on all lines. For the modeling, only parameters with physical meaning and no additional approximation factors are required. Even the small effects due to recombination of H-like atoms, which contribute only a few percent to the line intensity, can be used to explain consistently the recombination processes and hence the charge state distribution in a hot plasma. The measurements on fusion devices such as tokamaks or stellarators allow the comparison to the standard diagnostics for the same parameters. As these diagnostics are based on different physical processes, they provide sensitive tests for the atomic physics used for the synthetic spectra. They also allow distinguishing between different theoretical approaches to predict the spectra of other elements within the iso-electronic series. The modeling of the X-ray spectra of astronomical objects or solar flares, which are now frequently explored by X-ray satellite missions, is now more reliable. In these experiments, the statistical quality of the spectra is limited due to the finite observation time or the lifetime of... 

Additional secondary features. X-ray satellites, can appear in the spectra if a non-monochromatic source is used moreover X-ray ghost lines show up when the exciting photon originates from impurity elements in the X-ray source. 

The potential of the SW approach to systematize inneratomic properties and processes can be easily illustrated by reconsidering chemically induced nuclear lifetime variations which, among others, are of relevance to the calibration problem of Moessbauer isomer shifts. Highly excited atom states carrying single or multiple vacancies in inner shells form another promising subject of SW simulations. In the latter case the results of a DV-Xa study of the K-shell x-ray satellite intensities of metal fluorides can be used for a comparative assessment of both methods. 

The mode 1 is relevant to emissions of the A, C, D and E Auger and XO X-ray diagram lines, and the mode 2 is relevant to emissions of the B Auger and XI X-ray satellite lines, respectively. The mode 3 is divided into two, i.e. 3i and 32 which might relevant to Auger emissions of the F 2p or HOMO electron... 

Figure 15 Temperature dependence of the intensity and the transverse wave number of the 2 p and the X-ray satellite reflections in TTF-TCNQ. (Reproduced from S. Kagoshima et ah, J. Phys. Soc. Jpn., 41 (1976) 2061, Fig. 9)...

Methods for estimating intensity distributions of X-ray satellite spectra induced by accelerated ions with energies of a few MeV/amu are reviewed, where the orbitals responsible for X-ray emission are written in the molecular frame, not in the atomic frame. 

KEY WORDS PIXE, X-ray satellite. Electronic structure. Molecular orbital calculation, DV-Xo, Resonant orbital rearrangement... 

Fig. 4. Schematic spectra for observed (white) [9] and calculated (black) KlLn X-ray satellites. The incident ions were 1.4 MeV/amu C and O, and in the X-ray satellite intensity calculations the nuclear charges were assumed to be 6 and 8, respectively.

Fig. 5. Comparison between observed X-ray satellite spectra, same as those in Fig. 4, and calculated, where in the calculations the projectile nuclear charges were assumed to be the effective charge (E.C) numbers shown in parentheses.

The square of the molecular orbital coefficient for the K L" state is summarized in Table I. Also shown, in parentheses, is the energy (eV) relative to the energy of the highest occupied molecular orbital (HOMO). Here the orbital components are expressed as the sum of the squares of the partial expansion coefficients and of the overlap populations for the orbitals. From Table 1 it is easily seen that the K L X-ray line is mainly composed of three components each separated by leV. The observed X-ray satellite spectra for MgF and NiFj are shown in the solid lines in Figs. 8 and 9. Fig. 8 shows spectra induced by 2 MeV He impact, and Fig. 9 by 84 MeV impact. These excitation conditions produce mostly direct Coulomb ionization, not shake ionization. The observed spectra are now deconvoluted into K L" components. The rather broad K L line is further deconvoluted into three molecular orbital components each separated by... 

The present author proposed an the approximation method to explain the deviation of the X-ray satellite spectra intensity distributions from those described by eqs.(2),(5),(8) and (10), which we call Resonant Orbital Rearrangement (ROR) [6]. ROR was first used to explain the anomalous intensity distributions in F Ka satellite spectra which are emitted from a series of alkali-fluorides. Here resonance occurs during F Is ionization between the highest occupied molecular orbital (HOMO) in the KT. state and HOMO in the (K L +3s) state corresponding to the lowest unoccupied molecular orbital (LUMO) in the K L state. This leads to a reduction in the K L X-ray satellite intensity and to an increase in the K L X-ray diagram line intensity. Here (K L +3s) denotes the state with one vacancy in K shell and one vacancy in L shell and one electron in a 3s... 

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. 

There is direct evidence for accretion disks in AGNs from observations by the X-ray satellite ASCA of the Fe K line coming from many such sources (and lately also from Chandra and XMM Newton [20]). The line profile shows the asymmetry discussed in Sec. 2. Models which assume a profile for the disk emissivity distribution consistent with the specific energy profile of Fig. 3 are successful in reproducing the observed shape of the line from the Seyfert nuclei of NGC 3516 and NGC 3227 [21], In the latter case there is some indication that a rapidly rotating BH is involved because the strong asymmetry... 

XPS was used in Che Li project co characterize Che adsorption of THF on Li surfaces. It was performed in a Perkin-Elmer UHV chamber. The photon source was a Al-Mg dual anode X-Ray gun. The Mg anode was used in this work. The energy of the major Mg x-ray line is 1253.6 eV with a FWHM of 0.65 eV. Mg also has x-ray satellites at energies 8.4, 10.2 17.5, 20 and 48.5 eV higher than the major line. These satellites will cause corresponding satellite peaks of a major XPS peak. The gun was operated at 15-KeV and a power of 400 watts. The incident angle of the photons was typically 55 and the take-off angle of the photoelectrons was 0° with respect to the normal of a sample surface. 

COj dosing immediately after K evaporation at a temperature of 263 K displayed a major and a minor C(ls) peak at 284.0 and 289.0 eV, respectively, with additional features due to X-ray satellites of the main K peak at higher binding energies (see Panel Al in Figure 3.10). The area of the 284 eV peak was about five times larger than that of the 289 eV counterpart. This value is similar to that observed for the ratios of the areas of peaks... 

---