Spectroscopy

Energy dependence of 209-Bi fragmentation in relativistic nuclear collisions

The results of cross-section measurements for the reactions 209Bi(12C,X)Au, E=4.8 and 25.2 GeV and 209Bi(20Ne,X)Au, E=8.0 GeV are reported. The observed yields of the gold isotopes show a similar dependence on mass number for each reaction, differing slightly in the position of the centroid of the distribution. As the projectile energy increases, the inferred excitation energy of the primary residues remains the same or decreases slightly. This observation is in agreement with the predictions of the intranuclear cascade model of relativistic heavy ion collisions.

NUCLEAR REACTIONS 209Bi(12C,X)Au, E=4.8,25.2 GeV; 209Bi(20Ne,X)Au, E=8.0 GeV; measured Au isotopic distributions, relativistic heavy ions, target fragmentation, Ge(Li) spectroscopy.

Energy dependence of 209-Bi fragmentation in relativistic nuclear collisions, Aleklett, K., Morrissey D., Loveland W., McGaughey P., and Seaborg G. , Physical Review C, 3/1981, Volume 23, Issue 3, p.1044 - 1046, (1981)

On the Spectrum of Elementary Silicon

On the Spectrum of Elementary Silicon, Crookes, William , Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character (1905-1934), 8/1914, Volume 90, Issue 621, p.512 - 520, (2006)

On the Arc Spectrum of Scandium

On the Arc Spectrum of Scandium, Crookes, William , Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character (1905-1934), 6/1919, Volume 95, Issue 672, p.438 - 439, (2006)

Ig Nobel Prize for chemistry 2009

The 2009 chemistry prize goes to Javier Morales, Miguel Apátiga, and Victor M. Castaño (Universidad Nacional Autónoma de México) for creating diamonds from liquid — specifically from tequila.

Abstract from "Growth of Diamond Films from Tequila," Javier Morales, Miguel Apatiga and Victor M. Castano, 2008, arXiv:0806.1485. Diamond thin films were growth using Tequila as precursor by Pulsed Liquid Injection Chemical Vapor Deposition (PLI-CVD) onto both silicon (100) and stainless steel 304 at 850 C. The diamond films were characterized by Scanning Electron Microscopy (SEM) and Raman spectroscopy. The spherical crystallites (100 to 400 nm) show the characteristic 1332 cm-1 Raman band of diamond.

New form of carbon dioxide: amorphous

Only carbon from the Group 14 elements forms stable double bonds with oxygen under normal conditions. When frozen, carbon dioxide is known as "dry-ice". A non-molecular single-bonded crystalline form of carbon dioxide (phase V) exists at high pressure according to Italian and French researchers.1

Amorphous forms of silica (a-SiO2) and germania (a-GeO2) are known at ambient conditions but only recently has an amorphous, silica-like form of carbon dioxide, a-CO2. This is labelled a-carbonia and made by compression of CO2 at room temperature at pressures between 40 and 48 GPa (that's a staggering 400-500 thousand atmospheres).

During this compression, infrared spectra at temperatures up to 680 K show the progressive formation of C–O single bonds and the simultaneous disappearance of all infrared bands associated with molecular CO2. Raman and synchrotron X-ray diffraction measurements confirm the amorphous character of the CO2. Vibrational and diffraction data for a-SiO2 and a-GeO2 are closely related and calculations also suggest shows that a-CO2 is structurally homologous to a-silica (a-SiO2) and a-germania (a-GeO2).

This research helps to understanding the nature of the interiors of gas-giant planets where carbon dioxide may be squeezed at very high pressures. Maybe it could be used to make very hard glass because it is expected to be very stiff rather like diamond. The researchers ponder whether "small amounts of these new glasses could be of interest for technology applications like hard and resistant coatings for micro-electronics, for example."

Metal plated Venus?

Venus Cloud TopsVenus Cloud Tops
The BBC reported a few weeks ago that parts of Venus may be lead plated. David Whitehouse reports that

"The highlands of Venus are covered by a heavy metal 'frost', say planetary scientists from Washington University.

Because it is hot enough to melt lead at the surface, metals vaporise and condense at cooler, higher elevations.

This may explain why radar observations made by orbiting spacecraft show that the highlands are highly reflective.

Detailed calculations, to be published in the journal Icarus, suggest that lead and bismuth are to blame for giving Venus its bright, metallic skin."

Carbonate minerals on Mars

A NASA press release indicates that NASA's Spirit, the first of two Mars Exploration Rovers on the surface within Mars' Gusev crater, has identified carbonate minerals "in the rover's first survey of the site with its infrared sensing instrument, called the miniature thermal emission spectrometer or Mini-TES. Carbonates form in the presence of water, but it's too early to tell whether the amounts detected come from interaction with water vapor in Mars' atmosphere or are evidence of a watery local environment in the past, scientists emphasized."

"We came looking for carbonates. We have them. We're going to chase them," said Dr. Phil Christensen of Arizona State University, Tempe, leader of the Mini-TES team. Previous infrared readings from Mars orbit have revealed a low concentration of carbonates distributed globally. Christensen has interpreted that as the result of dust interaction with atmospheric water. First indications are that the carbonate concentration near Spirit may be higher than the Mars global average.

After the rover drives off its lander platform, infrared measurements it takes as it explores the area may allow scientists to judge whether the water indicated by the nearby carbonates was in the air or in a suspected ancient lake. http://marsrovers.jpl.nasa.gov/gallery/press/spirit/20040109a/graph-carb...

Does ET have the street lights on?

An artist's impression of a gas-giant planet orbiting the yellow Sun-like star HD 209458. Credit: G. Bacon, STScI.An artist's impression of a gas-giant planet orbiting the yellow Sun-like star HD 209458. Credit: G. Bacon, STScI.
Scientists crossed a new frontier in exo-planet research just last year when, using the Hubble Space Telescope, they detected sodium by its characteristic orange colour in the atmosphere of a large alien world orbiting the star HD 209458. Perhaps we are seeing ETs street lighting from a distance?

Beginning in 2006, a new telescope, Kepler (approved recently by NASA) will monitor about 100,000 nearby stars, searching for the slight dimming that occurs when an orbiting planet blocks some of the parent star's light. Because Kepler will be sensitive enough to detect planets as small as Earth, this celestial survey will give scientists an idea of how common Earth-like planets are - and identify candidates for further study.

This space telescope will use a technique called interferometry to dramatically reduce the obscuring glare from the planet's parent star, allowing scientists to see the planet itself, and so perhaps be able to analyse the atmospheres of those planets - required to detect signs of life.

WebElements: the periodic table on the WWW [http://www.webelements.com/]

Copyright 1993-2011 Mark Winter [The University of Sheffield and WebElements Ltd, UK]. All rights reserved.