Metastable innershell molecular state (MIMS)

Many problems in physical chemistry involve systems that are coupled to an environment, such as a molecule interacting with an adjacent surface, possibly resulting in meta-stable molecular states where electron density is transferred to the surface. Such systems can be described by non-Hermitian quantum mechanics (NHQM), where the Hamiltonian includes a complex potential. Within NHQM, one can also formulate the Hartree–Fock (HF) and Kohn–Sham (KS) methods and, as in the conventional theory, an effective independent-particle picture is employed. The crucial observation of the present study is that even for systems that are not coupled to an environment, in the non-Hermitian HF or KS equation, a single electron is interacting with the remaining electrons, which act as an environment, allowing for the exchange of current density between the one-electron and the remaining (N − 1)-electron system. The corresponding self-consistent states represent a new uncharted space of solutions to the HF and KS equations. We show that the additional solutions can have a physical interpretation and, therefore, extend the range of problems HF and KS can be applied to. If open-system HF and KS calculations are performed, the new class of solutions is always encountered, but this has also not been noted previously.

In this paper we study the soft X-ray (SXR) and hard X-ray (HXR) intensity produced in different insulator sleeves by a 4 kJ plasma focus device (APF) using filtered PIN-diodes and a fast scintillation detector. The experiments were performed for a great number of neon filling gas pressures at voltages of 11, 12 and 13 kV. Lengths of 40 and 50 mm look optimal to yield the most SXR intensity for the Pyrex and Quartz insulators respectively. The device appears to optimize much better for Pyrex insulator than the Quartz. For Pyrex and Quartz insulators, the lengths of 40 mm and 50 mm seem optimal to yield maximum HXR intensity, respectively.

The soft X-ray intensity of loops in active region cores and the corresponding footpoint, or moss, intensity observed in the EUV remain steady for several hours of observation. The steadiness of the emission has prompted many to suggest that the heating in these loops must also be steady, although no direct comparison between the observed X-ray and EUV intensities and the steady heating solutions of the hydrodynamic equations has yet been made. In this paper we perform these simulations and simultaneously model the X-ray and EUV moss intensities in one active region core with steady uniform heating. To perform this task, we introduce a new technique to constrain the model parameters using the measured EUV footpoint intensity to infer a heating rate. Using an ensemble of loop structures derived from magnetic field extrapolation of photospheric field, we associate each field line with an EUV moss intensity, then determine the steady uniform heating rate on that field line that reproduces the observed EUV intensity within 5% for a specific cross-sectional area, or filling factor. We then calculate the total X-ray filter intensities from all loops in the ensemble and compare this to the observed X-ray intensities. We complete this task iteratively to determine the filling factor that returns the best match to the observed X-ray intensities. We find that a filling factor of 8% and loops that expand with height provides the best agreement with the intensity in two X-ray filters, although the simulated SXT Al12 intensity is 147% the observed intensity and the SXT AlMg intensity is 80% the observed intensity. From this solution we determine the required heating rate scales as 0.29L−0.95. Finally, we discuss the future potential of this type of modeling, such as the ability to use density measurements to fully constrain filling factor, and its shortcomings, such as the requirement to use potential field extrapolations to approximate the coronal field.

Simulations of experiments on shock-induced melting, fragmentation and vaporization in aluminum and zinc targets are presented. A titanium impactor moves at a velocity of 10.4 km/s and causes melting of these materials in a shock wave. Under rarefaction thermodynamic path crosses the liquid–vapor coexistence boundary and enters into metastable liquid region. Liquid in a metastable state may undergo either liquid–vapor phase separation or mechanical fragmentation. Homogeneous nucleation theory and mechanical fragmentation criterion of Grady are taken into account to control the kinetics of these processes in our model. The first effect dominates in the vicinity of the critical point, the second one — at lower temperatures. Analysis of phase transitions and kinetics of phase separation is performed using thermodynamically complete equation of state with allowance for stable and metastable regions for all materials under consideration.

We report results of an analysis of the black hole (BH) candidate source X1755−338 made in 1989, 1990, and 1991 with Ginga, and in 1995 with ASCA. The spectra were well represented by a model consisting of a soft thermal emission from an accretion disk and a hard X-ray tail. The normalization of the multi-color disk, related to the inner disk radius, was similar to each other. The unabsorbed X-ray fluxes from the disk component in the 0.01–10 keV band were estimated to be 1.3 × 10−9, 3.0 × 10−9, 9.8 × 10−10, and 2.4 × 10−9 erg s−1 cm−2 in 1989, 1990, 1991, and 1995, respectively, and are proportional to $kT_{\rm in}^4$, where kTin is a temperature at the inner disk radius. Based on the standard accretion disk model for a non-rotating BH, our results suggest either a small BH mass or a large inclination angle. Otherwise, X1755−338 is a rotating BH. The hard X-ray intensity was found to be variable, while the soft X-ray intensity was stable. Although previous work showed the existence of an iron line at 6.7 keV, no clear iron line feature was found in any of the spectra. We infer that most of the iron line flux reported in the previous work was due to contamination of the Galactic diffuse X-ray emission.

On 23 May 1967 energetic (10–50 keV) solar flare X-rays were observed by the OGO-III ion chamber during the period 1808–2100 UT. The time-intensity profile for the X-ray event showed three distinct peaks at ≈1810, 1841 and 1942 UT. The second peak, which is equivalent to ≈2.9 × 10−3 ergs cm−2sec−1 above 20 keV, is the largest X-ray burst observed so far by the OGO-I and OGO-III ion chambers. The soft (2–12 A) X-ray observations reported by Van Allen (1968) also show similar peaks, roughly proportional in magnitude to the energetic X-ray peaks. However, the intensity of energetic X-rays peaked in each case 5–10 min earlier than the soft X-ray intensity indicating a relatively hard photon energy spectrum near the peak of the energetic X-ray emission. The corresponding time-intensity profile for the solar radio emission also showed three peaks in the microwave region nearly coincident with the energetic X-ray peaks. The third radio peak was relatively rich in the metric emission. Beyond this peak both the energetic X-rays and the microwave emission decayed with a time constant of ≈8 min while the corresponding time constant for the soft X-rays was ≈43 min. In view of the earlier findings about the energetic X-rays it is indicated that the 23 May solar X-ray event was similar to those observed earlier. During the 23 May event the integral energy flux spectrum at the time of peak intensity is found to be consistent with the form ∼e −E/E 0, E 0 being about 3.4 and 3.7 keV for the peaks at 1841 and 1942 UT, respectively. Assumption of a similar spectrum during the decay phase indicates that the spectral index E 0 decreased nearly exponentially with time.

A source of soft X-rays with an effective photon energy of 9 keV and a subnanosecond pulse width is built around a gas diode filled with atmospheric-pressure air and a UAEB-150 generator. A collector placed behind a grounded mesh electrode detects an electron beam and a pulse with positive polarity, the latter being due to an electric field surrounding the mesh. It is shown that the intensity of soft X-rays from the gas-diode-based source depends on the material of a massive potential anode; namely, it grows with an increase in the atomic number of the cathode material. In the case of a tantalum anode, X-ray photons with an effective energy of 9 and 17 keV contribute to the exposure dose.

Small GOES flares with intense hard X-ray emission

The celestial distribution of the intensity of diffuse soft X-rays is mapped by reference to a critical review of observations available. The soft X-rays of extragalactic origin are subtracted, taking the interstellar absorption into account. The distribution of the galactic component thus obtained shows irregularities, but the general behaviour can be accounted for in terms of a cylindrical distribution of the X-ray emissivity with the scale height of 100∼300 pc in the direction perpendicular to the galactic plane. Correlations with various celestial objects, such as supernova remnants, radio spurs, flaring stars, and so forth, are discussed.

X-ray lasing through high voltage, high current discharges in gas filled capillaries has been demonstrated in several laboratories. This method gives highest number of X-ray photons per pulse. The fast varying current and the jxB magnetic force compress the plasma towards the axis forming a hot, dense, line plasma, wherein under appropriate discharge conditions lasing occurs. At Laser Plasma Division, RRCAT, a program on high voltage capillary discharge had been started. The system consists of a 400 kV Marx bank, water line capacitor, spark gap and capillary chamber. The initial results of the emission of intense short soft X-ray pulses (5–10ns) from the capillary discharge are reported.

The stability of thin films of lead zirco-titanate (PZT) under intense soft X-ray beams is investigated by time-resolved photoelectron spectromicroscopy with a lateral resolution below 1 micrometer. Surface dissociation is observed when samples are irradiated with intense (5 × 1023 photons per s per m2) soft X-rays, with promotion of reduced lead on the surface. On areas exhibiting outwards polarization (P(+)), the reduced lead is formed at the expense of P(+)-PZT. On areas presenting co-existing P(+) states with areas without out-of-plane polarization (P(0)), the reduced lead is formed at the expense of the P(0)-PZT component, while the P(+)-PZT remains constant. The main dissociation mechanism was found to be triggered by 'hot' electrons in the conduction band, with energies exceeding the surface dissociation energies. Dissociation occurs basically when the electron affinity is larger than the dissociation energy of PbO (for P(+) areas) or PbO- (for P(0) areas). Such mechanisms may be adapted for dissociation of other molecules on surfaces of ferroelectric thin films or for quantifying the stability of ferroelectric surfaces interacting with other radiation, with applications in the fields of photocatalysis or photovoltaic devices.

Intense radiation from lasers has opened up many new areas of research in physics and chemistry, and has revolutionized optical technology. So far, most work in the field of nonlinear processes has been restricted to infrared, visible and ultraviolet light, although progress in the development of X-ray lasers has been made recently. With the advent of a free-electron laser in the soft-X-ray regime below 100 nm wavelength, a new light source is now available for experiments with intense, short-wavelength radiation that could be used to obtain deeper insights into the structure of matter. Other free-electron sources with even shorter wavelengths are planned for the future. Here we present initial results from a study of the interaction of soft X-ray radiation, generated by a free-electron laser, with Xe atoms and clusters. We find that, whereas Xe atoms become only singly ionized by the absorption of single photons, absorption in clusters is strongly enhanced. On average, each atom in large clusters absorbs up to 400 eV, corresponding to 30 photons. We suggest that the clusters are heated up and electrons are emitted after acquiring sufficient energy. The clusters finally disintegrate completely by Coulomb explosion.

We report on the results of ASCA observation of the Galactic jet source GRO J1655−40 performed in 1997 Feb. Previous ASCA observations of GRO J1655−40 in 1994 and 1995 revealed the presence of Kα resonance absorption lines from highly ionized iron ions in the X-ray spectra [1]. The center energy of the absorption line varied in association with the change of X-ray intensity: it was that of Kα line of H-like irons and of He-like irons when the X-ray intensity was high (2.2 Crab) and low (0.27–0.57 Crab), respectively. These results suggest that the high temperature plasma producing the absorption lines is located in a non-spherical configuration and is photo-ionized by X-ray radiations. In order to investigate the geometry of the plasma in detail, we performed a long observation of this source from 1997 Feb. 26 to Feb. 28 to cover its full orbital period (2.6 days). The average X-ray intensity was 0.9 Crab and a blend of two absorption lines from H-like and He-like irons was detected. This is consistent with the photo-ionization scenario in relation to the previous observations. We found that the absorption line features exist over the full orbital phase. This fact indicates that the plasma responsible for line absorptions distributes symmetrically around the rotation axis of the accretion disk.

Toxic and carcinogenic substances were produced during laser application in medicine for the cutting and evaporation of tissue. The laser smoke presents a danger potential for the medical staff and the patients. The laser tissue interaction process was investigated by means of laser spectroscopic measurements which give the possibility of measuring metastable molecular states directly as a prerequisite to understand and to influence fundamental laser tissue interaction processes in order to reduce the amount of harmful chemicals. Highly excited atomic and molecular states and free radicals (CN, OH, C<SUB>2</SUB>, CH, CH<SUB>2</SUB>) have been detected applying spontaneous and laser induced fluorescence methods. It was found that the formation of harmful substances in the laser plumes can be reduced significantly by optimization of the surrounding gas atmosphere. A high content of oxygen or water in the interaction zone has been found, in agreement with the results of classical and analytical methods, as a suitable way to decrease pollutant emission. The experimental methods and the principal results are applicable not only in laser medicine but in laser material treatment generally.

view Abstract Citations (8) References (22) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Soft X-ray observations of two BL Lacertae objects : Markarian 421 and 501. Singh, K. P. ; Garmire, G. P. Abstract This paper reports on the soft X-ray (0.15-2.8 keV) observations of two BL Lacertae-type objects, viz., Mrk 421 and Mrk 501. The observations were made with the low-energy detectors on the HEAO 1 satellite during the period 1977 August-1978 December. Steep, soft X-ray power-law spectra with photon index Gamma = 3 are found for both Mrk 421 and Mrk 501. The power-law models are found to give a significantly better fit than the thermal models to the observed pulse-height spectra of Mrk 421 and Mrk 501. Day-to-day soft X-ray (0.25 keV band) intensity variations are observed only in Mrk 501. No significant change is found in Gamma from both the BL Lac objects during the period of observations. However, the sum of all the X-ray observations from 1976 until 1980 can be understood in terms of two spectral components of variable intensity to account for the X-ray emission observed between 0.15 and 20 keV from Mrk 421 and Mrk 501. Publication: The Astrophysical Journal Pub Date: October 1985 DOI: 10.1086/163516 Bibcode: 1985ApJ...297..199S Keywords: Bl Lacertae Objects; Emission Spectra; X Ray Sources; Bremsstrahlung; Synchrotron Radiation; Astrophysics full text sources ADS | data products SIMBAD (2) NED (2)