245 research outputs found
Intensity distribution in rotational line spectra
Completely resolved Doppler-free rotational line spectra of six vibronic two-photon bands in benzene C6 H6 and C6 D6 are presented. The excited final states possess different excess energies in S1 (1567 to 2727 cm−1 ) and are embedded in dense manifolds of background states with differing densities of states (1<rho<60 1/cm−1 ). The bands are analyzed by a statistical procedure. The intensity distribution of several hundreds of lines of each band is investigated. It is found that all weakly perturbed bands display a similar, peaked intensity distribution while in strongly perturbed bands the number of lines decreases monotonically with increasing intensity. The origin of this difference is discussed in terms of coupling to the many background states. The Journal of Chemical Physics is copyrighted by The American Institute of Physics
Prolongation on regular infinitesimal flag manifolds
Many interesting geometric structures can be described as regular
infinitesimal flag structures, which occur as the underlying structures of
parabolic geometries. Among these structures we have for instance conformal
structures, contact structures, certain types of generic distributions and
partially integrable almost CR-structures of hypersurface type. The aim of this
article is to develop for a large class of (semi-)linear overdetermined systems
of partial differential equations on regular infinitesimal flag manifolds a
conceptual method to rewrite these systems as systems of the form
, where is a linear connection
on some vector bundle over and is a
(vector) bundle map. In particular, if the overdetermined system is linear,
will be a linear connection on and hence the dimension of
its solution space is bounded by the rank of . We will see that the rank of
can be easily computed using representation theory.Comment: 35 pages; typos corrected and minor changes, final version to appear
in International Journal of Mathematic
Irradiation of benzene molecules by ion-induced and light-induced intense fields
Benzene, with its sea of delocalized -electrons in the valence orbitals,
is identified as an example of a class of molecules that enable establishment
of the correspondence between intense ion-induced and laser-light-induced
fields in experiments that probe ionization dynamics in temporal regimes
spanning the attosecond and picosecond ranges.Comment: 4 ps figure
Push-pull thiophene chromophores for electro-optic applications: from 1D linear to beta-branched structures
We report the synthesis and characterization of a novel series of push-pull chromophores bearing 1D linear and beta-branched thiophenes as pi-conjugated spacers between a 2, 2, 4, 7-tetramethyl-1, 2, 3, 4-tetrahydroquinoline electron donor unit and dicyano- and tricyanovinylene electron acceptor groups. The effect of the introduction of beta-thiophenes on the linear and nonlinear (NLO) optical properties as well as electrochemical and thermal data is studied in detail by performing a comparative study between the branched and 1D linear systems. In addition, a parallel DFT computational study is used to evaluate structure-property relationships. The non-linear optical behavior of the molecules both in solution and in solid state as electro-optic (EO) films using a guest-host approach shows very promising performance for electro-optic applications with high molecular first hyperpolarizabilities (mu beta) of 4840 x 10(-48) esu and electro-optic coefficients r(33) reaching 650 pm V-1. One highlight is that the electro-optic films of the beta-branched chromophores are superior in terms of thermal stability in device operation as measured by a transmissive modified reflective Teng-Man method. This work provides guidelines for the design of improved electro-optic materials including beta-branched chromophores which could be useful for practical EO applications, where both enhanced beta and r(33) values together with chemical and thermal stability are necessary
V-shaped pyranylidene/triphenylamine-based chromophores with enhanced photophysical, electrochemical and nonlinear optical properties
We report the synthesis and comprehensive study of two chromophores based on 4H-pyranylidene moiety as a part of the p-conjugated spacer. Triphenylamine (TPA) acts as donor and tricarbonitrile-based electron-accepting groups complete these V-shaped D-A-D architectures (A, acceptor; D, donor). Their electrochemical, photophysical and nonlinear optical properties are analyzed in detail by using a joint experimental and theoretical approach. The two chromophores exhibit near-infrared fluorescence, large Stokes shift, enhanced emission in tetrahydrofuran/water mixtures and good photostability. Additionally, the dimerization of triphenylamine groups to tetraphenylbenzidine (TPB) takes place upon electrochemical and chemical oxidation showing their peculiar electrochemical behavior and film formation capabilities. Interestingly, high molecular first hyperpolarizabilities and two-photon absorption cross-sections were found, highlighting their potential applications in electro-optical devices. Overall, our work demonstrates that these near-infrared (NIR) fluorescent chromophores are versatile materials with a myriad of applications ranging from optoelectronics to biological applications. © 2021 The Royal Society of Chemistry
Enhanced Expression of Janus Kinase–Signal Transducer and Activator of Transcription Pathway Members in Human Diabetic Nephropathy
OBJECTIVE—Glomerular mesangial expansion and podocyte loss are important early features of diabetic nephropathy, whereas tubulointerstitial injury and fibrosis are critical for progression of diabetic nephropathy to kidney failure. Therefore, we analyzed the expression of genes in glomeruli and tubulointerstitium in kidney biopsies from diabetic nephropathy patients to identify pathways that may be activated in humans but not in murine models of diabetic nephropathy that fail to progress to glomerulosclerosis, tubulointerstitial fibrosis, and kidney failure
Quadrupole Moment Measurements of TSD1 and TSD2 Bands in \u3csup\u3e167\u3c/sup\u3eLu
The triaxial strongly deformed (TSD) bands in 167Lu were populated by the 123Sb(48Ca, 4n) reaction with a beam energy of 203 MeV. Gamma rays, requiring fivefold or more in prompt coincidence, were detected with the Gammasphere spectrometer. Of particular interests are TSD bands 1 and 2 which have previously been interpreted as zero phonon and one phonon wobbling bands, respectively. Using the Doppler shift attenuation method (DSAM), a preliminary transition quadrupole moment of 6.9+0.3−0.3 eb was extracted for the TSD1 band. Data analysis continues for TSD2 which is considerably more weakly populated
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