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Full-Text Articles in Physical Sciences and Mathematics
The High Pressure Dependence Of X-Ray Induced Decomposition Of Cadmium Oxalate, Adrian F. Lua Sanchez, Petrika Cifligu, Marc Graff, Michael Pravica, Pradip K. Bhowmik, Changyong Park, Egor Evlyukhin
The High Pressure Dependence Of X-Ray Induced Decomposition Of Cadmium Oxalate, Adrian F. Lua Sanchez, Petrika Cifligu, Marc Graff, Michael Pravica, Pradip K. Bhowmik, Changyong Park, Egor Evlyukhin
Physics & Astronomy Faculty Research
The high proclivity of x rays to destabilize and distort molecular structures has been previously utilized in the synthesis of novel compounds. Here, we show that x-ray induced decomposition of cadmium oxalate induces chemical and structural transformations only at 0.5 and 1 GPa. Using x-ray diffraction and Raman spectroscopy, the synthesized product is identified as cadmium carbonate with cadmium oxalate remnants, which is stable under ambient conditions. At ambient and >1 GPa pressures, only degradation of the electronic density distribution is observed. The transformation kinetics are examined in terms of Avrami’s model, which demonstrates that despite the necessity of high …
Statistical Measurements Of Dispersion Measure Fluctuations Of Frbs, Siyao Xu, David H. Weinberg, Bing Zhang
Statistical Measurements Of Dispersion Measure Fluctuations Of Frbs, Siyao Xu, David H. Weinberg, Bing Zhang
Physics & Astronomy Faculty Research
Extragalactic fast radio bursts (FRBs) have large dispersion measures (DMs) and are unique probes of intergalactic electron density fluctuations. By using the recently released First CHIME/FRB Catalog, we reexamined the structure function (SF) of DM fluctuations. It shows a large DM fluctuation similar to that previously reported in Xu & Zhang, but no clear correlation hinting toward large-scale turbulence is reproduced with this larger sample. To suppress the distortion effect from FRB distances and their host DMs, we focus on a subset of CHIME catalog with DM < 500 pc cm-3. A trend of nonconstant SF and nonzero correlation function (CF) at angular separations θ less than 10 is seen, but with large statistical uncertainties. The difference found between SF and that derived from CF at θ ≲ 10 can be ascribed to the large statistical uncertainties or the density inhomogeneities on scales on the order of 100 Mpc. The possible correlation of electron density fluctuations and inhomogeneities of density distribution should be tested when several thousands of FRBs are available.
Free-Free Absorption In Hot Relativistic Flows: Application To Fast Radio Bursts, Esha Kundu, Bing Zhang
Free-Free Absorption In Hot Relativistic Flows: Application To Fast Radio Bursts, Esha Kundu, Bing Zhang
Physics & Astronomy Faculty Research
Magnetic flares create hot relativistic shocks outside the light cylinder radius of a magnetized star. Radio emission produced in such a shock or at a radius smaller than the shock undergoes free–free absorption while passing through the shocked medium. In this work, we demonstrate that this free–free absorption can lead to a negative drift in the frequency-time spectra. Whether it is related to the downward drift pattern observed in fast radio bursts (FRBs) is unclear. However, if the FRB down-drifting is due to this mechanism then it will be pronounced in those shocks that have isotropic kinetic energies ≳1044 erg. …