Application of Multilayer Structures to the Determination of Optical Constants in the X-Ray, Soft X-Ray and Extreme Ultra Violet Spectral Ranges

1988 ◽  
Vol 143 ◽  
Author(s):  
Troy W. Barbee
Keyword(s):  
Cross Sections ◽  
Optical Constants ◽  
Extreme Ultraviolet ◽  
Ultra Violet ◽  
Multilayer Structures ◽  
X Rays ◽  
X Ray ◽  
Spectral Ranges ◽  
Scattering Cross Sections

AbstractThe dispersion of x-rays (XR), soft x-rays (SXR) and extreme ultraviolet (EUV) light by multilayer structures is dependent on the scattering and absorption cross-sections of the elements used to synthesize the multilayer. In this paper it will be shown that this dependence provides a means for the accurate experimental determination of the optical constants of the multilayer constituents. Two specific approaches will be presented and discussed. First, it will be shown that detailed analysis of the energy dependence of the reflectivity of a simple depth periodic multilayer allows the unfolding of the optical constants. Secondly a new optic structure, the multilayer diffraction grating, will be described and it will be demonstrated that such combined microstructure optics allow the scattering cross-sections of the multilayer constituents to be accurately determined over broad spectral ranges.

Destruction of C2H4O2 isomers in ice-phase by X-rays: Implication on the abundance of acetic acid and methyl formate in the interstellar medium

2017 ◽  
Vol 13 (S332) ◽  
pp. 418-424
Author(s):  
Marina G. Rachid ◽  
K. Faquine ◽  
S. Pilling
Keyword(s):  
Acetic Acid ◽  
Cross Sections ◽  
Methyl Formate ◽  
X Rays ◽  
Formation Cross Section ◽  
X Ray ◽  
Synchrotron Light ◽  
The Difference ◽  
Astrophysical Ices

AbstractC2H4O2 isomers, methyl formate (HCOOCH3), acetic acid (CH3COOH) and glycoaldehyde (HOCH2CHO), have been detected in a lot of sources in ISM. However, their abundances are very different, with methyl formate much more abundant than the other two isomers. This fact may be related to the different destruction by ionizing radiation of these molecules. The goal of this work is experimentally study the photodissociation processes of methyl formate and acetic acid ices when exposed to broadband soft X-ray from 6 up to 2000 eV. The experiments were performed coupled to the SGM beamline in the Brazilian Synchrotron Light Source (LNLS/CNPEM) at Campinas, Brazil. The simulated astrophysical ices (12K) were monitored throughout the experiment using infrared vibrational spectroscopy. The analysis of processed ices allowed the determination of the effective destruction cross sections of the parent molecules as well as the effective formation cross section of daughter molecular species. The relative abundance between acetic acid and methyl formate (NCH3COOH/NHCOOCH3) in different astronomical scenarios and their column density evolution in the presence of X-rays were calculated and our results suggests that such radiation field can be one of the factors that explain the difference in the isomers C2H4O2 abundances. We also quantified the daugther species after the establishment of a chemical equilibrium in the samples.

scholarly journals Extreme-ultraviolet- and X-Ray-driven Photochemistry of Gaseous Exoplanets

2022 ◽  
Vol 3 (1) ◽  
pp. 1
Author(s):  
Daniele Locci ◽  
Antonino Petralia ◽  
Giuseppina Micela ◽  
Antonio Maggio ◽  
Angela Ciaravella ◽  
...  
Keyword(s):  
Cross Sections ◽  
Atmospheric Chemistry ◽  
Extreme Ultraviolet ◽  
X Rays ◽  
Stellar Spectrum ◽  
X Ray ◽  
Spectral Bands ◽  
Wide Range ◽  
Chemical Conditions ◽  
Ultraviolet Photons

Abstract The interaction of exoplanets with their host stars causes a vast diversity in bulk and atmospheric compositions and physical and chemical conditions. Stellar radiation, especially at the shorter wavelengths, drives the chemistry in the upper atmospheric layers of close orbiting gaseous giants, providing drastic departures from equilibrium. In this study, we aim at unfolding the effects caused by photons in different spectral bands on the atmospheric chemistry. This task is particularly difficult because the characteristics of chemical evolution emerge from many feedbacks on a wide range of timescales, and because of the existing correlations among different portions of the stellar spectrum. In describing the chemistry, we have placed particular emphasis on the molecular synthesis induced by X-rays. The weak X-ray photoabsorption cross sections of the atmospheric constituents boost the gas ionization to pressures inaccessible to vacuum and extreme-ultraviolet photons. Although X-rays interact preferentially with metals, they produce a secondary electron cascade able to ionize efficiently hydrogen- and helium-bearing species, giving rise to a distinctive chemistry.

Coherent and incoherent scattering of low-energy X-ray photons in the atomic region 13 ≤ Z ≤ 82

1996 ◽  
Vol 74 (1-2) ◽  
pp. 10-16 ◽  
Author(s):  
D. V. Rao ◽  
R. Cesareo ◽  
G. E. Gigante ◽  
D. V. Rao ◽  
G. E. Gigante
Keyword(s):  
Cross Sections ◽  
Detection System ◽  
Form Factors ◽  
Coherent Scattering ◽  
Incoherent Scattering ◽  
X Rays ◽  
Bremsstrahlung Radiation ◽  
X Ray ◽  
Scattering Cross ◽  
Scattering Cross Sections

Coherent- and incoherent-scattering cross sections for the elements Al, Cu, Y, In, Au, and Pb were measured using nearly monoenergetic unpolarized 35.86 and 39.96 keV X-ray beams with high-resolution Si (Li) detectors. Bremsstrahlung radiation from an X-ray tube was used to excite nearly monoenergetic X-rays in secondary targets. To improve the efficiency of the detection system the excitation source, detector, and the target assembly were placed in a vacuum chamber and a pressure of 10−2 mbar was maintained throughout the measurements. This system considerably reduced the background and scattering effects and improved the monochromacy. Experimental coherent-scattering cross sections are compared with the normalized integrated coherent-scattering cross sections calculated using the relativistic, nonrelativistic, and relativistic-modified form factors. Experimental incoherent-scattering cross sections are compared with the theoretical values, calculated using the nonrelativistic incoherent-scattering function. Good correspondence is observed between experimental and theoretical values in the given energy region.

Determination of K shell absorption parameters for some lanthanides using the X-ray attenuation method

2015 ◽  
Vol 93 (12) ◽  
pp. 1532-1540 ◽  
Author(s):  
F. Akman ◽  
R. Durak ◽  
M.R. Kaçal
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Experimental Results ◽  
Secondary Source ◽  
X Rays ◽  
Strength Parameters ◽  
X Ray ◽  
Total Attenuation ◽  
First Time

The total attenuation cross section at the K edge, absorption jump ratio, jump factor, Davisson–Kirchner ratio, and oscillator strength parameters for the K shell were determined by measuring the total attenuation cross sections around the K edge for Pr, Nd2O3, and Sm. The measurements were performed in a secondary excitation geometry using the Kα2, Kα1, Kβ1, and Kβ2 X-rays (in the region from 31.817 to 55.293 keV) from different secondary source targets excited by the 59.54 keV γ-photons from an 241Am annular source. It is the first time that the Davisson–Kirchner ratio values have been determined for present samples. The experimental results were compared with the theoretically calculated and other available experimental results.

scholarly journals X-ray and ion emission studies from subnanosecond laser-irradiated SiO2 aerogel foam targets

2017 ◽  
Vol 35 (3) ◽  
pp. 505-512 ◽  
Author(s):  
C. Kaur ◽  
S. Chaurasia ◽  
A.A. Pisal ◽  
A.K. Rossall ◽  
D.S. Munda ◽  
...  
Keyword(s):  
Laser Energy ◽  
Laser System ◽  
Line Emission ◽  
Plasma Temperature ◽  
X Rays ◽  
Plasma Parameters ◽  
X Ray ◽  
Spectral Ranges ◽  
Ion Emission

AbstractIn this experiment, a comparative study of ion and X-ray emission from both a SiO2 aerogel foam and a quartz target is performed. The experiment is performed using Nd:glass laser system operated at laser energy up to 15 J with a pulse duration of 500 ps with focusable intensity of 1013–1014 W/cm2 on target. X-ray fluxes in different spectral ranges (soft and hard) are measured by using X-ray diodes covered with Al filters of thickness 5 µm (0.9–1.56 keV) and 20 µm (3.4–16 keV). A 2.5 times enhancement in soft X-ray flux (0.9–1.56 keV) and a decrease of 1.8 times in hard X rays (3.4–16 keV) for 50 mg/cc SiO2 aerogel foam is observed compared with the solid quartz. A decrease in the flux of the K-shell line emission spectrum of soft X rays is noticed in the case of the foam targets. The high-resolution K-shell spectra (He-like) of Si ions in both the cases are analyzed for the determination of plasma parameters by comparing with FLYCHK simulations. The estimated plasma temperature and density are Tc = 180 eV, ne = 7 × 1020 cm−3 and Tc = 190 eV, ne = 4 × 1020 cm−3 for quartz and SiO2 aerogel foam, respectively. To measure the evolution of the plasma moving away from the targets, four identical ion collectors are placed at different angles (22.5, 30, 45, and 67.5°) from target normal. The angular distribution of the thermal ions are scaled as cosnθ with respect to target normal, where n = 3.8 and 4.8 for the foam and quartz, respectively. The experimental plasma volume measured from the ion collectors and shadowgraphy images are verified by a two-dimensional Eulerian radiative–hydrodynamic simulation (POLLUX code).

scholarly journals Fine-structure of soft X-ray absorption edges - I—Li, Mg, Ni, Cu metals

1937 ◽  
Vol 161 (906) ◽  
pp. 420-440 ◽  
Keyword(s):  
Fine Structure ◽  
Conduction Electron ◽  
Wave Length ◽  
Ultra Violet ◽  
Short Wave ◽  
Experimental Investigations ◽  
X Rays ◽  
X Ray ◽  
X Ray Absorption

The borderland region between ultra-violet light and X-rays, particularly from about 100 to 300 A, is very suitable for obtaining spectroscopic information regarding the electronic structure of metals, or solids generally. The first step towards this problem consists in the determination of the intensity distribution in the soft X-ray emission bands, which represent transitions from the filled conduction-electron levels of a metal into a vacant inner shell. We thus obtain information relating to the distribution with energy of these filled levels. The most complete experimental investigations of the emission bands are those of Siegbahn and Magnusson (1934) and of O’Bryan and Skinner (1934) for the metals Li, Be, Na, Mg, Al, Si. Subse­quent work showed that the extension of these results to heavier metals is very difficult, because the Auger effect reduces the intensity of the emission by a large factor. The complementary problem is that of absorption, in which we are dealing with transitions from an inner shell of the metal into one of the unoccupied conduction-electron levels of the metal. The probability of such an absorption process is closely connected with the density of the unoccupied levels as a function of energy. The experimental problem therefore consists of the determination of the variation in the absorption coefficient of radiation by electrons of a given inner shell as a function of wave-length; or, as it may be called, the determination of the fine-structure on the short wave-length side of an X-ray absorption edge of a metal.

Multilayer Monochromators for the Soft X-Ray and Extreme Ultraviolet

1988 ◽  
Vol 143 ◽  
Author(s):  
Troy W. Barbee ◽  
Piero Pianetta
Keyword(s):  
Thin Films ◽  
Cross Sections ◽  
Extreme Ultraviolet ◽  
Diffraction Gratings ◽  
Multilayer Structures ◽  
Absorption Cross ◽  
Optical Elements ◽  
X Ray ◽  
Long Period ◽  
Transmission Measurements

Simple multilayer structures and multilayer diffraction gratings are now of sufficient quality to be used as optical elements in synchrotron radiation source instrumentation. In this paper results obtained with a multilayer two element monochromator will be presented. Three specific types of results will be discussed. First, transmission measurements of the absorption cross-sections of elemental thin films in the energy range 50 to 2000 eV will be presented and used to demonstrate the performance of the monochromator. Second, application of this monochromator in x-ray lithography research will be described and the advantages of the broad bandpass of multilayer optics demonstrated. Third, use of this monochromator in scattering studies of long period structures will be discussed. The potential for the use of multilayer diffraction gratings in high resolution monochromator applications will also be considered.

scholarly journals Sub-Kilovolt X-Ray Calibration of Photographic Film

1974 ◽  
Vol 18 ◽  
pp. 146-158 ◽  
Author(s):  
Louis N. Koppel
Keyword(s):  
Photon Energy ◽  
Ultra Violet ◽  
Photographic Film ◽  
Photon Flux ◽  
X Rays ◽  
X Ray ◽  
Response Data ◽  
Continuous Beams ◽  
Titanium Nickel

AbstractThe x-ray spectroscopy of laser-generated plasmas can be applied to photon energies of less than 1 keV, provided calibrations of the response of energy discriminators and detectors are performed in the sub-kilovolt region. In our application we use photographic film to monitor the intensity of radiation dispersed by a curved lead stearate crystal. We have determined the response to sub-kilovolt x-rays of two types of film, Kodak No-Screen and the special vacuum ultra-violet Kodak type 101-01. This calibration was obtained by exposing samples of film to continuous beams of nearly monochromatic characteristic radiation from an array of targets. The fluorescent radiations were the K series of carbon and magnesium and the L series of titanium, nickel, cobalt and copper. The response data are presented as a series of characteristic curves, plotting for each film type and photon energy the net diffuse photographic density as a function of the photon flux incident on the film. The processing of all film was in accordance with the manufacturer's suggestions. We attempt to characterize the accuracy and reproducibility of these data. The data demonstrate the greater sensitivity of the type 101-01 to sub-kilovolt x-rays.The intensity and spectral purity of the incident fluorescent beams were monitored by a thin-window gas proportional counter that used flowing propane gas at sub-atmospheric pressures. We describe the procedures and results of a determination of the quantum efficiency of this counter as a function of photon energy.

Sign in / Sign up

Export Citation Format

Share Document