17,492 research outputs found
Oscillator strengths and line widths of dipole-allowed transitions in ¹⁴N₂ between 89.7 and 93.5 nm
Line oscillator strengths in the 20 electric dipole-allowed bands of ¹⁴N₂ in the 89.7–93.5nm (111480–106950cm⁻¹) region are reported from photoabsorptionmeasurements at an instrumental resolution of ∼6mÅ (0.7cm⁻¹) full width at half maximum. The absorptionspectrum comprises transitions to vibrational levels of the 3pσᵤc′₄¹Σᵤ⁺, 3pπᵤc³Πᵤ, and 3sσgo₃¹ΠᵤRydberg states and of the b′¹Σᵤ⁺ and b¹Πᵤ valence states. The J dependences of band f values derived from the experimental line f values are reported as polynomials in J′(J′+1) and are extrapolated to J′=0 in order to facilitate comparisons with results of coupled Schrödinger-equation calculations. Most bands in this study are characterized by a strong J dependence of the band f values and display anomalous P-, Q-, and R-branch intensity patterns. Predissociation line widths, which are reported for 11 bands, also exhibit strong J dependences. The f value and line width patterns can inform current efforts to develop comprehensive spectroscopic models that incorporate rotational effects and predissociation mechanisms, and they are critical for the construction of realistic atmospheric radiative-transfer models.This work was supported in part by NASA Grant No.
NNG05GA03G to Wellesley College and Australian Research
Council Discovery Program Grant No. DP0558962
A family of tridiagonal pairs and related symmetric functions
A family of tridiagonal pairs which appear in the context of quantum
integrable systems is studied in details. The corresponding eigenvalue
sequences, eigenspaces and the block tridiagonal structure of their matrix
realizations with respect the dual eigenbasis are described. The overlap
functions between the two dual basis are shown to satisfy a coupled system of
recurrence relations and a set of discrete second-order difference
equations which generalize the ones associated with the Askey-Wilson orthogonal
polynomials with a discrete argument. Normalizing the fundamental solution to
unity, the hierarchy of solutions are rational functions of one discrete
argument, explicitly derived in some simplest examples. The weight function
which ensures the orthogonality of the system of rational functions defined on
a discrete real support is given.Comment: 17 pages; LaTeX file with amssymb. v2: few minor changes, to appear
in J.Phys.A; v3: Minor misprints, eq. (48) and orthogonality condition
corrected compared to published versio
Memory and chaos in an Ising spin glass
The non-equilibrium dynamics of the model 3d-Ising spin glass
- FeMnTiO - has been investigated from the temperature
and time dependence of the zero field cooled magnetization recorded under
certain thermal protocols. The results manifest chaos, rejuvenation and memory
features of the equilibrating spin configuration that are very similar to those
observed in corresponding studies of the archetypal RKKY spin glass Ag(Mn). The
sample is rapidly cooled in zero magnetic field, and the magnetization recorded
on re-heating. When a stop at constant temperature is made during the
cooling, the system evolves toward its equilibrium state at this temperature.
The equilibrated state established during the stop becomes frozen in on further
cooling and is retrieved on re-heating. The memory of the aging at is not
affected by a second stop at a lower temperature
. Reciprocally, the first equilibration at has no influence on
the relaxation at , as expected within the droplet model for domain
growth in a chaotic landscape.Comment: REVTeX style; 4 pages, 4 figure
Oscillator strengths and line widths of dipole-allowed transitions in ¹⁴N₂ between 86.0 and 89.7 nm
Oscillator strengths of 23 electric-dipole-allowed bands of ¹⁴N₂ in the 86.0–89.7 nm (111 480–116 280 cm⁻¹) region are reported from synchrotron-based photoabsorptionmeasurements at an instrumental resolution of 6.5×10⁻⁴ nm (0.7 cm⁻¹) full width at half maximum.Partial support for this research was provided by the
Australian Research Council Discovery Program through
Grant No. DP0558962 and by NASA Grant No.
NNX08AE786 to Wellesley College
Effects of hydrogen bonding on supercooled liquid dynamics and the implications for supercooled water
The supercooled state of bulk water is largely hidden by unavoidable
crystallization, which creates an experimentally inaccessible temperature
regime - a 'no man's land'. We address this and circumvent the crystallization
problem by systematically studying the supercooled dynamics of hydrogen bonded
oligomeric liquids (glycols), where water corresponds to the chain-ends alone.
This novel approach permits a 'dilution of water' by altering the hydrogen bond
concentration via variations in chain length. We observe a dynamic crossover in
the temperature dependence of the structural relaxation time for all glycols,
consistent with the common behavior of most supercooled liquids. We find that
the crossover becomes more pronounced for increasing hydrogen bond
concentrations, which leads to the prediction of a marked dynamic transition
for water within 'no man's land' at T~220 K. Interestingly, the predicted
transition thus takes place at a temperature where a so called 'strong-fragile'
transition has previously been suggested. Our results, however, imply that the
dynamic transition of supercooled water is analogous to that commonly observed
in supercooled liquids. Moreover, we find support also for the existence of a
secondary relaxation of water with behavior analogous to that of the secondary
relaxation observed for the glycols.Comment: 20 pages, 5 figures; corrected typos, title changed, small clarifying
text changes, two labels removed from Fig. 2
Weak formulation for singular diffusion equation with dynamic boundary condition
In this paper, we propose a weak formulation of the singular diffusion
equation subject to the dynamic boundary condition. The weak formulation is
based on a reformulation method by an evolution equation including the
subdifferential of a governing convex energy. Under suitable assumptions, the
principal results of this study are stated in forms of Main Theorems A and B,
which are respectively to verify: the adequacy of the weak formulation; the
common property between the weak solutions and those in regular problems of
standard PDEs.Comment: 23 page
On the high energy proton spectrum measurements
The steepening of the proton spectrum beyond 1000 GeV and the rise in inelastic cross sections between 20 and 600 GeV observed by the PROTON-1-2-3 satellite experiments were explained by systematic effects of energy dependent albedo (backscatter) from the calorimeter
Elastic precursor of the transformation from glycolipid-nanotube to -vesicle
By the combination of optical tweezer manipulation and digital video
microscopy, the flexural rigidity of single glycolipid "nano" tubes has been
measured below the transition temperature at which the lipid tubules are
transformed into vesicles. Consequently, we have found a clear reduction of the
rigidity obviously before the transition as temperature increasing. Further
experiments of infrared spectroscopy (FT-IR) and differential scanning
calorimetry (DSC) have suggested a microscopic change of the tube walls,
synchronizing with the precursory softening of the nanotubes.Comment: 9 pages, 6 figure
Electronic correlation in the infrared optical properties of the quasi two dimensional -type BEDT-TTF dimer system
The polarized optical reflectance spectra of the quasi two dimensional
organic correlated electron system -(BEDT-TTF)Cu[N(CN)],
Br and Cl are measured in the infrared region. The former shows the
superconductivity at 11.6 K and the latter does the
antiferromagnetic insulator transition at 28 K. Both the
specific molecular vibration mode of the BEDT-TTF molecule and
the optical conductivity hump in the mid-infrared region change correlatively
at 38 K of -(BEDT-TTF)Cu[N(CN)]Br, although
no indication of but the insulating behaviour below 50-60 K are found in -(BEDT-TTF)Cu[N(CN)]Cl. The
results suggest that the electron-molecular vibration coupling on the
mode becomes weak due to the enhancement of the itinerant
nature of the carriers on the dimer of the BEDT-TTF molecules below ,
while it does strong below because of the localized carriers on
the dimer. These changes are in agreement with the reduction and the
enhancement of the mid-infrared conductivity hump below and , respectively, which originates from the transitions between the upper
and lower Mott-Hubbard bands. The present observations demonstrate that two
different metallic states of -(BEDT-TTF)Cu[N(CN)]Br are
regarded as {\it a correlated good metal} below including the
superconducting state and {\it a half filling bad metal} above . In
contrast the insulating state of -(BEDT-TTF)Cu[N(CN)]Cl
below is the Mott insulator.Comment: 8 pages, 7 figure
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