Absorption Of Blackbody Radiation Research Articles

Symmetry Breaking in Sticky Collisions between Ultracold Molecules.

Ultracold molecules undergo "sticky collisions" that result in loss even for chemically nonreactive molecules. Sticking times can be enhanced by orders of magnitude by interactions that lead to nonconservation of nuclear spin or total angular momentum. We present a quantitative theory of the required strength of such symmetry-breaking interactions based on classical simulation of collision complexes. We find static electric fields as small as 10 V/cm can lead to nonconservation of angular momentum, while we find nuclear spin is conserved during collisions. We also compute loss of collision complexes due to spontaneous emission and absorption of black-body radiation, which are found to be slow.

Spectral optical characteristics of nanoparticles for effective extinction of black body radiation with high temperatures

Different types of fires and high-temperature technological processes are the sources of intense dangerous optical radiation, which can be modeled by black body radiation. The strongly enhanced extinction and absorption of black body radiation with high temperatures in the range 1000–2000 K in wide spectral interval of 200–6000 nm by nanoparticles are of significant science and technical interest. The investigation and analysis have been conducted of plasmonic characteristics of core-shell nanoparticles for radiation wavelengths in the spectral interval 200–6000 nm and in the range of NP radii ~25–200 nm with the shell thickness 5 nm on the base of computer modeling. These results highlight the possibility of novel core-shell NiO-Ni nanoparticles with the radii of about ~75–175 nm for effective application as attenuators for radiation in the optical spectrum 200–6000 nm from sources with temperatures in the range 1000–2000 K. Fe3O4-Au and SiO2-Au nanoparticles show possibility for extinction of radiation with the temperatures of 1500, 2000 K and less possibility for extinction radiation with 1000 K.

Blackbody-Radiation-Induced Population Transfer Dynamics from Highly Vibrationally Excited Levels of the E 0g+ (3P2) Ion-Pair State of I2.

We report the decay dynamics from the highly excited vibrational levels of the E 0g+ (3P2) ion-pair state of I2. Strong UV fluorescence belonging to the D 0u+ (3P2) → X 1Σg+ transition was observed upon the excitation of the E 0g+ (3P2) (vE = 77 and 78) state. The vibrational levels populated in the D 0u+ (3P2) state were found to be located at slightly higher energies than the vibrational levels of the laser-excited E 0g+ (3P2) state. The vibrational levels populated in the D 0u+ (3P2) state were restricted to those which have relatively large Franck-Condon factors between the laser-prepared vibronic levels. The absorption andstimulated emission rate in the presence of thermal radiation strongly suggests that the population in the D 0u+ (3P2) state was induced by the absorption of blackbody radiation. The energy partitioning process in the high vibrational levels in the E 0g+ (3P2) state was found to be totally different from that in the lower levels (vE = 0-2) where amplified spontaneous emission was a major relaxation pathway.

Chemical reactivity on gas-phase metal clusters driven by blackbody infrared radiation.

We report the observation of chemical reactions in gas-phase Rh(n)(N2O)m(+) complexes driven by absorption of blackbody radiation. The experiments are performed under collision-free conditions in a Fourier transform ion cyclotron resonance mass spectrometer. Mid-infrared absorption by the molecularly adsorbed N2O moieties promotes a small fraction of the cluster distribution sufficiently to drive the N2O decomposition reaction, leading to the production of cluster oxides and the release of molecular nitrogen. N2O decomposition competes with molecular desorption and the branching ratios for the two processes show marked size effects, reflecting variations in the relative barriers. The rate of decay is shown to scale approximately linearly with the number of infrared chromophores. The experimental findings are interpreted in terms of calculated infrared absorption rates assuming a sudden-death limit.

Far infrared stimulated emission from the ns and nf Rydberg states of NO

We report directional far-infrared emission from the υ = 0 vibrational levels of the 9sσ, 10sσ, 11sσ, 9f, and 10f Rydberg states of NO in the gas phase. The emission around 28 and 19 μm from the 9f state was identified as the downward 9f → 8g and subsequent 8g → 7f cascade transitions, respectively. The emission around 38 and 40 μm from the 10f state was identified as the 10f → 9g and 10f → 9dσπ transition, respectively. Following the excitation of the 9sσ, 10sσ, and 11sσ states, the emission around 40, 60, and 83 μm was assigned as the 9sσ → 8pσ, 10sσ → 9pσ, and 11sσ → 10pσ transitions, respectively. In addition to these emission systems originated from the laser-prepared levels, we found the emission bands from the 8f, 9f, and 10f states which are located energetically above the 9sσ, 10sσ, and 11sσ states, respectively. This observation suggests that the upward 8f ← 9sσ, 9f ← 10sσ, and 10f ← 11sσ optical excitation occurs. Since the energy differences between nf and (n + 1)sσ states correspond to the wavelength longer than 100 μm, the absorption of blackbody radiation is supposed to be essential for these upward transitions.

Trapping cold molecular hydrogen

Translationally cold H(2) molecules excited to non-penetrating |M(J)| = 3 Rydberg states of principal quantum number in the range 21-37 have been decelerated and trapped using time-dependent inhomogeneous electric fields. The |M(J)| = 3 Rydberg states were prepared from the X (1)Σ(+)(u)(v = 0, J = 0) ground state using a resonant three-photon excitation sequence via the B (1)Σ(+)(u)(v = 3, J = 1) and I (1)Π(g) (v = 0, J = 2) intermediate states and circularly polarized laser radiation. The circular polarization of the vacuum ultraviolet radiation used for the B ← X transition was generated by resonance-enhanced four-wave mixing in xenon and the degree of circular polarization was determined to be 96%. To analyse the deceleration and trapping experiments, the Stark effect in Rydberg states of molecular hydrogen was calculated using a matrix diagonalization procedure similar to that presented by Yamakita et al., J. Chem. Phys., 2004, 121, 1419. Particular attention was given to the prediction of zero-field positions of low-l states and of avoided crossings between Rydberg-Stark states with different values of |M(J)|. The calculated Stark maps and probabilities for diabatic traversal of the avoided crossings were used as input to Monte-Carlo particle-trajectory simulations. These simulations provide a quantitatively satisfactory description of the experimental data and demonstrate that particle loss caused by adiabatic traversals of avoided crossings between adjacent |M(J)| = 3 Stark states of H(2) is small at principal quantum numbers beyond n = 25. The main source of trap losses was found to be from collisional processes. Predissociation following the absorption of blackbody radiation is estimated to be the second most important trap-loss mechanism at room temperature, and trap loss by spontaneous emission is negligible under our experimental conditions.

Precision measurements with polar molecules: the role of the black body radiation

In the perspective of the outstanding developments of high-precision measurements of fundamental constants using polar molecules related to ultimate checks of fundamental theories, we investigate the possibly counterproductive role of black-body radiation on a series of diatomic molecules which would be trapped and observed for long durations. We show that the absorption of black-body radiation at room temperature may indeed limit the lifetime of trapped molecules prepared in a well-defined quantum state. Several examples are treated, corresponding to pure rotational absorption, pure vibrational absorption or both. We also investigate the role of a black-body radiation-induced energy shift on molecular levels and how it could affect high-precision frequency measurements.

Black body radiation induced hydrogen formation in hydrated vanadium cations V+(H2O)n

Hydrated vanadium cations V+(H2O)n, n = 5–30, are stored in the collision-free environment of an FT-ICR mass spectrometer and their reactions due to absorption of black body radiation are studied. Besides the loss of water ligands, the clusters show two different intracluster redox reactions, whose branching ratios are strongly size-dependent. Oxidation to the +II state results in V(OH)+(H2O)n ions, and a concurrent release of atomic hydrogen. Alternatively V(OH)2+(H2O)n clusters can form leaving vanadium in the +III state, common in aqueous solutions, and simultaneously molecular H2 evaporates from the cluster. This behavior reflects the properties of transition metals, and the ability of vanadium to form stable compounds in a variety of oxidation states, and differs from the previously studied intracluster reactions involving the hydrated monovalent main group metals Mg+ and Al+. These only react to their preferred oxidation states, MgOH+ and Al(OH)2+, respectively.

On the dissociation and conformation of gas-phase methonium ions

The dissociation pathways of both doubly and singly charged methonium ions, (CH 3) 3N + -(CH 2) n - +N(CH 3) 3·X − ( n = 6, 10; X = Br, I, and OAc), are measured using blackbody infrared radiative dissociation (BIRD) and SORI-CAD in a Fourier transform mass spectrometer. SORI-CAD of the doubly charged decamethonium ions results primarily in the formation of even electron ions by hydrogen rearrangements. In contrast, homolytic bond cleavage to form two odd electron ions is highly favored in the hexamethonium ion, presumably due to increased Coulomb repulsion in this ion. For BIRD of the singly charged salts, ions are mass selected and dissociated by heating the vacuum chamber to elevated temperatures. Under the low pressure conditions of our experiment, energy is transferred from the chamber walls to the ions by the absorption of blackbody radiation. From the temperature dependence of the unimolecular rate constants for dissociation, Arrhenius activation energies in the zero-pressure limit are obtained. The primary dissociation pathways correspond to counterion substitution reactions which result in loss of N(CH 3) 3 and CH 3X. For hexamethonium and decamethonium with X = Br or I, the branching ratios for these pathways differ dramatically; the ratio of loss of N(CH 3) 3 and CH 3Br is 3.8 and 0.4 for hexamethonium and decamethonium bromide, respectively. The hexamethonium acetate salt has a branching ratio of 0.1. The Arrhenius activation energies for hexamethonium (Br or I) and decamethonium (Br or I) are 0.9 and 1.0 eV, respectively. This value for hexamethonium acetate is 0.6 eV. Molecular dynamics simulations and Monte Carlo conformation searching are used to obtain the lowest energy structures of hexamethonium and decamethonium bromide. These calculations indicate that the methonium ion folds around the counterion to form a cyclic salt-bridge structure in which both quaternary nitrogens interact with the oppositely charged counterion. The significantly different branching ratios observed for these ions is attributed to the large change in orientation of the counterion with respect to the ammonium centers as the number of methylene groups in these ions increases. Similar ion conformational differences appear to explain the fragmentation for the OAc counter ion as well.

Spontaneous Unimolecular Dissociation of Small Cluster Ions, (H3O+)Ln and Cl-(H2O)n (n = 2-4), under Fourier Transform Ion Cyclotron Resonance Conditions

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSpontaneous Unimolecular Dissociation of Small Cluster Ions, (H3O+)Ln and Cl-(H2O)n (n = 2-4), under Fourier Transform Ion Cyclotron Resonance ConditionsDetlef Thoelmann, D. Scott Tonner, and Terrance B. McMahonCite this: J. Phys. Chem. 1994, 98, 8, 2002–2004Publication Date (Print):February 1, 1994Publication History Published online1 May 2002Published inissue 1 February 1994https://doi.org/10.1021/j100059a002RIGHTS & PERMISSIONSArticle Views188Altmetric-Citations134LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (406 KB) Get e-Alerts

On collective absorption of black-body radiation by Rydberg atoms

A weak cooperative absorption of black-body radiation by a system of N identical two-level Rydberg atoms is considered as a result of a dynamical equilibrium between the radiation and the atoms, the time of interaction being much smaller than the Rabi period.

Spectral Absorption of Water Vapor and Carbon Dioxide Mixtures in the 2.7 Micron Band

An investigation of the spectral absorption characteristics of water vapor and carbon dioxide mixtures in the 2.7 micron band is described. The absorption of black body radiation by gas mixtures in the central region of a high temperature furnace was measured. The optical path length of 30 cm was bounded by NaCl windows mounted in water-cooled holders. The temperature was essentially uniform in the central one-third of the test cell, and decreased to between 400 800 K at the ends. Representative spectral transmissivity distributions obtained for central temperatures ranging from 1000 to 2200 K and pressures from 0.25 to 3 atm for four different mixture ratios of water vapor and carbon dioxide are presented. Results showed the interaction effect on spectral transmissivity to be greatest at the band center where the maximum change from around 0.40 to 0.48 was observed for approximately equimolar mixtures at a total pressure of 0.5 atm. Since this occurs over a limited wave number range, spectral transmissivities of such mixtures can be acceptably approximated by ignoring the interaction. Spectral distributions predicted from published data for spectral H2O and CO2 absorption coefficients and line half-width to spacing ratios are in good agreement with measured distributions.