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Notations and conventions in molecular spectroscopy: part 1. General spectroscopic notation
The field of Molecular Spectroscopy was surveyed in order to determine a set of
conventions and symbols which are in common use in the spectroscopic literature. This
document, which is Part I in a series, establishes the notations and conventions used for
general spectroscopic notations and deals with quantum mechanics, quantum numbers
(vibrational states, angular momentum and energy levels), spectroscopic transitions, and
miscellaneous notations (e.g. spectroscopic terms). Further parts will follow, dealing inter
alia with symmetry notation, permutation and permutation-inversion symmetry notation,
vibration-rotation spectroscopy and electronic spectroscopy
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Notations and conventions in molecular spectroscopy: part 2. Symmetry notation
The field of Molecular Spectroscopy was surveyed in order to determine a set of
conventions and symbols which are in common use in the spectroscopic literature. This
document, which is Part 2 in a series, establishes the notations and conventions used for the
description of symmetry in rigid molecules, using the Schoenflies notation. It deals firstly
with the symmetry operators of the molecular point groups (also drawing attention to the
difference between symmetry operators and elements). The conventions and notations of the
molecular point groups are then established, followed by those of the representations of these
groups as used in molecular spectroscopy. Further parts will follow, dealing inter alia with
permutation and permutation-inversion symmetry notation, vibration-rotation spectroscopy
and electronic spectroscopy
β-Alanine Supplementation Has No Effect on Rowing Performance in College Age Athletes
Please view abstract in the attached PDF file
AKARI near-infrared spectroscopy of the aromatic and aliphatic hydrocarbon emission features in the galactic superwind of M 82
Aims. We investigate the properties of hydrocarbon grains in the galactic
superwind of M 82. Methods. With AKARI, we performed near-infrared (2.5 - 4.5
um) spectroscopic observations of 34 regions in M 82 including its northern and
southern halos. Results. Many of the spectra show strong emission at 3.3 um due
to polycyclic aromatic hydrocarbons (PAHs) and relatively weak features at 3.4
- 3.6 um due to aliphatic hydrocarbons. In particular, we clearly detect the
PAH 3.3 um emission and the 3.4 - 3.6 um features in halo regions, which are
located at a distance of 2 kpc away from the galactic center. We find that the
ratios of the 3.4 - 3.6 um features to the 3.3 um feature intensity
significantly increase with distance from the galactic center, while the ratios
of the 3.3 um feature to the AKARI 7 um band intensity do not. Conclusions. Our
results clearly confirm the presence of small PAHs even in a harsh environment
of the halo of M 82. The results also reveal that the aliphatic hydrocarbons
emitting the 3.4 - 3.6 um features are unusually abundant in the halo,
suggesting that small carbonaceous grains are produced by shattering of larger
grains in the galactic superwind.Comment: 5 pages, 3 figures, 1 table, accepted for publication in A&
Dust Dynamics in Compressible MHD Turbulence
We calculate the relative grain-grain motions arising from interstellar
magnetohydrodynamic (MHD) turbulence. The MHD turbulence includes both fluid
motions and magnetic fluctuations. While the fluid motions accelerate grains
through hydro-drag, the electromagnetic fluctuations accelerate grains through
resonant interactions. We consider both incompressive (Alfv\'{e}n) and
compressive (fast and slow) MHD modes and use descriptions of MHD turbulence
obtained in Cho & Lazarian (2002). Calculations of grain relative motion are
made for realistic grain charging and interstellar turbulence that is
consistent with the velocity dispersions observed in diffuse gas, including
cutoff of the turbulence from various damping processes. We show that fast
modes dominate grain acceleration, and can drive grains to supersonic
velocities. Grains are also scattered by gyroresonance interactions, but the
scattering is less important than acceleration for grains moving with
sub-Alfv\'{e}nic velocities. Since the grains are preferentially accelerated
with large pitch angles, the supersonic grains will be aligned with long axes
perpendicular to the magnetic field. We compare grain velocities arising from
MHD turbulence with those arising from photoelectric emission, radiation
pressure and H thrust. We show that for typical interstellar conditions
turbulence should prevent these mechanisms from segregating small and large
grains. Finally, gyroresonant acceleration is bound to preaccelerate grains
that are further accelerated in shocks. Grain-grain collisions in the shock may
then contribute to the overabundance of refractory elements in the composition
of galactic cosmic rays.Comment: 15 pages, 17 figure
Blackbody-radiation-assisted molecular laser cooling
The translational motion of molecular ions can be effectively cooled
sympathetically to temperatures below 100 mK in ion traps through Coulomb
interactions with laser-cooled atomic ions. The distribution of internal
rovibrational states, however, gets in thermal equilibrium with the typically
much higher temperature of the environment within tens of seconds. We consider
a concept for rotational cooling of such internally hot, but translationally
cold heteronuclear diatomic molecular ions. The scheme relies on a combination
of optical pumping from a few specific rotational levels into a ``dark state''
with redistribution of rotational populations mediated by blackbody radiation.Comment: 4 pages, 5 figure
Speckle interferometry and radiative transfer modelling of the Wolf-Rayet star WR 118
WR 118 is a highly evolved Wolf-Rayet star of the WC10 subtype surrounded by
a permanent dust shell absorbing and re-emitting in the infrared a considerable
fraction of the stellar luminosity. We present the first diffraction-limited
2.13micron speckle interferometric observations of WR 118 with 73 mas
resolution. The speckle interferograms were obtained with the 6m telescope at
the Special Astrophysical Observatory. The two-dimensional visibility function
of the object does not show any significant deviation from circular symmetry.
The visibility curve declines towards the diffraction cut-off frequency to 0.66
and can be approximated by a linear function. Radiative transfer calculations
have been carried out to model the spectral energy distribution, given in the
range of 0.5-25micron, and our 2.13micron visibility function, assuming
spherical symmetry of the dust shell. Both can be fitted with a model
containing double-sized grains (``small'' and ``large'') with the radii of a =
0.05micron and 0.38micron, and a mass fraction of the large grains greater than
65%. Alternatively, a good match can be obtained with the grain size
distribution function n(a)~a^-3, with a ranging between 0.005micron and
0.6micron. At the inner boundary of the modelled dust shell (angular diameter
(17 +/- 1)mas), the temperature of the smallest grains and the dust shell
density are 1750K +/- 100K and (1 +/- 0.2)x10^-19 g/cm^3, respectively. The
dust formation rate is found to be (1.3 +/- 0.5)x10^-7 Msol/yr assuming Vwind =
1200 km/s.Comment: 6 pages including 4 PostScript figures, also available from
http://www.mpifr-bonn.mpg.de/div/ir-interferometry/publications.html;
accepted for publication in Astronomy & Astrophysic
Boron and nitrogen isotope effects on hexagonal boron nitride properties
The unique physical, mechanical, chemical, optical, and electronic properties
of hexagonal boron nitride (hBN) make it a promising two-dimensional material
for electronic, optoelectronic, nanophotonic, and quantum devices. Here we
report on the changes in hBN's properties induced by isotopic purification in
both boron and nitrogen. Previous studies on isotopically pure hBN have focused
on purifying the boron isotope concentration in hBN from its natural
concentration (approximately 20 at B, 80 at B) while
using naturally abundant nitrogen (99.6 at N, 0.4 at N),
i.e. almost pure N. In this study, we extend the class of
isotopically-purified hBN crystals to N. Crystals in the four
configurations, namely hBN, hBN, hBN,
and hBN, were grown by the metal flux method using boron and
nitrogen single isotope () enriched sources, with nickel plus chromium
as the solvent. In-depth Raman and photoluminescence spectroscopies demonstrate
the high quality of the monoisotopic hBN crystals with vibrational and optical
properties of the N-purified crystals at the state of the art of
currently available N-purified hBN. The growth of high-quality
hBN, hBN, hBN, and hBN
opens exciting perspectives for thermal conductivity control in heat
management, as well as for advanced functionalities in quantum technologies.Comment: 13 pages, 7 figure
Isotopic control of the boron-vacancy spin defect in hexagonal boron nitride
We report on electron spin resonance (ESR) spectroscopy of boron-vacancy
(V) centers hosted in isotopically-engineered hexagonal boron
nitride (hBN) crystals. We first show that isotopic purification of hBN with
N yields a simplified and well-resolved hyperfine structure of
V centers, while purification with B leads to narrower ESR
linewidths. These results establish isotopically-purified hBN
crystals as the optimal host material for future use of V spin
defects in quantum technologies. Capitalizing on these findings, we then
demonstrate optically-induced polarization of N nuclei in
hBN, whose mechanism relies on electron-nuclear spin mixing in
the V ground state. This work opens up new prospects for future
developments of spin-based quantum sensors and simulators on a two-dimensional
material platform.Comment: 6 pages, 3 figur
Abundance analysis for long period variables. Velocity effects studied with O-rich dynamic model atmospheres
(abbreviated) Measuring the surface abundances of AGB stars is an important
tool for studying the effects of nucleosynthesis and mixing in the interior of
low- to intermediate mass stars during their final evolutionary phases. The
atmospheres of AGB stars can be strongly affected by stellar pulsation and the
development of a stellar wind, though, and the abundance determination of these
objects should therefore be based on dynamic model atmospheres. We investigate
the effects of stellar pulsation and mass loss on the appearance of selected
spectral features (line profiles, line intensities) and on the derived
elemental abundances by performing a systematic comparison of hydrostatic and
dynamic model atmospheres. High-resolution synthetic spectra in the near
infrared range were calculated based on two dynamic model atmospheres (at
various phases during the pulsation cycle) as well as a grid of hydrostatic
COMARCS models. Equivalent widths of a selection of atomic and molecular lines
were derived in both cases and compared with each other. In the case of the
dynamic models, the equivalent widths of all investigated features vary over
the pulsation cycle. A consistent reproduction of the derived variations with a
set of hydrostatic models is not possible, but several individual phases and
spectral features can be reproduced well with the help of specific hydrostatic
atmospheric models. In addition, we show that the variations in equivalent
width that we found on the basis of the adopted dynamic model atmospheres agree
qualitatively with observational results for the Mira R Cas over its light
cycle. The findings of our modelling form a starting point to deal with the
problem of abundance determination in strongly dynamic AGB stars (i.e.,
long-period variables).Comment: 13 pages, 22 figures, accepted for publication in A&
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