Search results for "Ground state"
showing 10 items of 928 documents
Sub-critical InAs layers on metamorphic InGaAs for single quantum dot emission at telecom wavelengths
2014
We report on the design, the growth by MBE and the optical and morphological characterization of metamorphic InAs/InGaAs quantum dots (QD) with a density low enough to allow single dot characterization without the need of complex litographic steps to isolate single QDs. InAs sub-critical coverages were deposited on InxGa1-xAs metamorphic buffers (MBs) and the transition from 2D growth to 3D island nucleation was monitored by reflection high energy electron diffraction (RHEED). We discuss the fundamental differences of the sub-critical growth method compared with the Stranski-Krastanow one, also by considering available theoretical models. AFM confirmed that the density of QDs can be control…
Computational evidence in favor of a two-state, two-mode model of the retinal chromophore photoisomerization
2000
In this paper we use ab initio multiconfigurational second-order perturbation theory to establish the intrinsic photoisomerization path model of retinal chromophores. This is accomplished by computing the ground state ( S 0 ) and the first two singlet excited-state ( S 1 , S 2 ) energies along the rigorously determined photoisomerization coordinate of the rhodopsin chromophore model 4- cis -γ-methylnona-2,4,6,8-tetraeniminium cation and the bacteriorhodopsin chromophore model all- trans -hepta-2,4,6-trieniminium cation in isolated conditions. The computed S 2 and S 1 energy profiles do not show any avoided crossing feature along the S 1 reaction path and maintain an energy gap >20 kcal⋅…
Trans-to-cis photoisomerization of cyclocurcumin in different environments rationalized by computational photochemistry
2020
International audience; Cyclocurcumin is a turmeric component that attracted much less attention compared to the well known curcumin. In spite of the less deep charcaterization of its properties, cyclocurcumin has shown promising anticancer effects when used in combination with curcumin. Especially, due to its peculiar molecular structure, cyclocurcumin can be regarded as an almost ideal photoswitch, whose capabilities can also be exploited for relevant biological applications. Here, by means of state-of-the-art computational methods for electronic excited-state calculations (TD-DFT, MS-CASPT2, XMS-CASPT2) we analyze in detail the absorption and photoisomerization pathways leading from the …
Study of ordered hadron chains with the ATLAS detector
2017
The analysis of the momentum difference between charged hadrons in high-energy proton-proton collisions is performed in order to study coherent particle production. The observed correlation pattern agrees with a model of a helical QCD string fragmenting into a chain of ground-state hadrons. A threshold momentum difference in the production of adjacent pairs of charged hadrons is observed, in agreement with model predictions. The presence of low-mass hadron chains also explains the emergence of charge-combination-dependent two-particle correlations commonly attributed to Bose-Einstein interference. The data sample consists of 190 μb-1 of minimum-bias events collected with proton-proton colli…
Charm-quark fragmentation fractions and production cross section at midrapidity in pp collisions at the LHC
2022
Physical review / D 105(1), L011103 (2022). doi:10.1103/PhysRevD.105.L011103
The observation of vibrating pear-shapes in radon nuclei
2019
6 pags., 4 fig.s, 1 tab. -- Open Access funded by Creative Commons Atribution Licence 4.0
New Nuclear Magnetic Moment of Bi209 : Resolving the Bismuth Hyperfine Puzzle
2018
A recent measurement of the hyperfine splitting in the ground state of Li-like ${^{208}\mathrm{Bi}}^{80+}$ has established a ``hyperfine puzzle''---the experimental result exhibits a $7\ensuremath{\sigma}$ deviation from the theoretical prediction [J. Ullmann et al., Nat. Commun. 8, 15484 (2017); J. P. Karr, Nat. Phys. 13, 533 (2017)]. We provide evidence that the discrepancy is caused by an inaccurate value of the tabulated nuclear magnetic moment (${\ensuremath{\mu}}_{I}$) of $^{209}\mathrm{Bi}$. We perform relativistic density functional theory and relativistic coupled cluster calculations of the shielding constant that should be used to extract the value of ${\ensuremath{\mu}}_{I}(^{209…
Breakdown of the Reduction of the Rovibrational Hamiltonian: The Case of S18O2F2
2009
Abstract The ground state rotational spectrum of the near-spherical top molecule S18O2F2 (sulfuryl fluoride) has been measured from 50 to 700 GHz. As for the parent isotopologue, S16O2F2 [K. Sarka, J. Demaison, L. Margules, I. Merke, N. Heineking, H. Burger, H. Ruland, J. Mol. Spectrosc. 200 (2000) 55–64], it was necessary to use a non-reduced Hamiltonian in order to obtain a satisfactory fit. It was possible to determine six quartic centrifugal distortion constants (instead of five for a standard asymmetric top) and five sextic constants (one of them not existing in the reduced Hamiltonian) could also be determined. This ground state level has also been analysed thanks to a tensorial forma…
Observation of the 2+ isomer in Co52
2016
We report the first observation of the ${2}^{+}$ isomer in $^{52}\mathrm{Co}$, produced in the $\ensuremath{\beta}$ decay of the ${0}^{+}$, $^{52}\mathrm{Ni}$ ground state. We have observed three $\ensuremath{\gamma}$ rays at 849, 1910, and 5185 keV characterizing the $\ensuremath{\beta}$ de-excitation of the isomer. We have measured a half-life of 102(6) ms for the isomeric state. The Fermi and Gamow-Teller transition strengths for the $\ensuremath{\beta}$ decay of $^{52m}\mathrm{Co}$ to $^{52}\mathrm{Fe}$ have been determined. We also add new information on the $\ensuremath{\beta}$ decay of the ${6}^{+}$, $^{52}\mathrm{Co}$ ground state, for which we have measured a half-life of 112(3) ms.
Experimental study of isomeric intruder 12+ states in At197,203
2017
A newly observed isomeric intruder ${\textonehalf{}}^{+}$ state $[{T}_{\textonehalf{}}=3.5(6)\phantom{\rule{0.16em}{0ex}}\mathrm{ms}]$ is identified in $^{203}\mathrm{At}$ using a gas-filled recoil separator and fusion-evaporation reactions. The isomer is depopulated through a cascade of $E3$ and mixed $M1/E2$ transitions to the ${9/2}^{\ensuremath{-}}$ ground state, and it is suggested to originate from the $\ensuremath{\pi}{({s}_{\textonehalf{}})}^{\ensuremath{-}1}$ configuration. In addition, the structures above the ${\textonehalf{}}^{+}$ state in $^{203}\mathrm{At}$ and $^{197}\mathrm{At}$ are studied using in-beam $\ensuremath{\gamma}$-ray spectroscopy, recoil-decay tagging, and recoi…