Search results for " state"
showing 10 items of 5973 documents
Hyperfine interaction in the Autler-Townes effect: The formation of bright, dark, and chameleon states
2017
This paper is devoted to clarifying the implications of hyperfine (HF) interaction in the formation of adiabatic (i.e., ``laser-dressed'') states and their expression in the Autler-Townes (AT) spectra. We first use the Morris-Shore model [J. R. Morris and B. W. Shore, Phys. Rev. A 27, 906 (1983)] to illustrate how bright and dark states are formed in a simple reference system where closely spaced energy levels are coupled to a single state with a strong laser field with the respective Rabi frequency ${\mathrm{\ensuremath{\Omega}}}_{S}$. We then expand the simulations to realistic hyperfine level systems in Na atoms for a more general case when non-negligible HF interaction can be treated as…
Defect Luminescence of LiBaF3 Perovskites
2000
Blue and red luminescence of undoped LiBaF3 crystals was studied. A broad, isotropic photoluminescence band centered at 410 nm can be excited by 210 nm — 275 nm light in as grown crystals. After X-irradiation at RT a new narrower, anisotropic luminescence band appears at 425 mn which has an additional excitation band at 290 nm. The X-irradiation also creates the F- type centres and anisotropic centres with an absorption band at 630 nm and a luminescence band at 700 nm. No F- centre luminescence is observed. All the other centres mentioned act as radiative recombination centers as well. It is speculated that the origin of the blue luminescence is due to oxygen defects and that the red lumine…
Magnetic coupling and spin topology in linear oxalato-bridged tetranuclear chromium(III)–copper(II) complexes with aromatic diimine ligands
2013
Abstract A novel heterotetranuclear chromium(III)–copper(II) complex of formula {[CrIII(bpy)(ox)2]2CuII2(bpy)2(ox)}·6H2O (1) has been synthesized by the ligand exchange reaction between Ph4P[CrIII(bpy)(ox)2]·H2O and [CuII(bpy)2(NO3)]NO3·MeOH in methanol (bpy = 2,2′-bipyridine; ox2− = oxalate dianion). The X-ray crystal structure of 1 consists of neutral oxalato-bridged CrIII2Cu2II zigzag entities which are formed by the monodentate coordination of two [CrIII(bpy)(ox)2]− mononuclear anionic units through one of its two oxalato groups toward a [CuII2(bpy)2(ox)]2+ dinuclear cationic moiety featuring relatively long axial bonds at the square pyramidal CuII ions. Variable temperature (2.0–300 K)…
CONSTRUCTION OF METASTABLE STATES IN QUANTUM ELECTRODYNAMICS
2004
In this paper, we construct metastable states of atoms interacting with the quantized radiation field. These states emerge from the excited bound states of the non-interacting system. We prove that these states obey an exponential time-decay law. In detail, we show that their decay is given by an exponential function in time, predicted by Fermi's Golden Rule, plus a small remainder term. The latter is proportional to the (4+β)th power of the coupling constant and decays algebraically in time. As a result, though it is small, it dominates the decay for large times. A central point of the paper is that our remainder term is significantly smaller than the one previously obtained in [1] and as…
Rydberg excitation of trapped cold ions: a detailed case study
2011
We provide a detailed theoretical and conceptual study of a planned experiment to excite Rydberg states of ions trapped in a Paul trap. The ultimate goal is to exploit the strong state dependent interactions between Rydberg ions to implement quantum information processing protocols and to simulate the dynamics of strongly interacting spin systems. We highlight the promises of this approach when combining the high degree of control and readout of quantum states in trapped ion crystals with the novel and fast gate schemes based on interacting giant Rydberg atomic dipole moments. We discuss anticipated theoretical and experimental challenges on the way towards its realization.
Dicyclopentaannelated Hexa-peri-hexabenzocoronenes with a Singlet Biradical Ground State
2021
Abstract Synthesis of two dicyclopentaannelated hexa‐peri‐hexabenzocoronene (PHBC) regioisomers was carried out, using nonplanar oligoaryl precursors with fluorenyl groups: mPHBC 8 with two pentagons in the “meta”‐configuration was obtained as a stable molecule, while its structural isomer with the “para”‐configuration, pPHBC 16, could be generated and characterized only in situ due to its high chemical reactivity. Both PHBCs exhibit low energy gaps, as reflected by UV‐vis‐NIR absorption and electrochemical measurements. They also show open‐shell singlet ground states according to electron paramagnetic resonance (EPR) measurements and density functional theory (DFT) calculations. The use of…
Functional diversity of decomposer organisms in relation to primary production
1998
Abstract The term `biodiversity' is claimed to lack connections to a serious scientific background. In this work, we approached the concept of biodiversity from a functional point of view by asking: “At what level of the ecological organization (species, trophic species/feeding guilds, trophic levels etc.) should reduction in biodiversity matter to bring about visible changes in ecosystem performance?” We investigate the concepts of `functional diversity' and `ecosystem performance' in relation to feeding habits (such as fungivory, detritivory etc.) of soil fauna and plant growth. After analysing the results of a number of microcosm studies, we came into the following conclusions: (i) troph…
Analysis of multi degree of freedom systems with fractional derivative elements of rational order
2014
In this paper a novel method based on complex eigenanalysis in the state variables domain is proposed to uncouple the set of rational order fractional differential equations governing the dynamics of multi-degree-of-freedom system. The traditional complex eigenanalysis is appropriately modified to be applicable to the coupled fractional differential equations. This is done by expanding the dimension of the problem and solving the system in the state variable domain. Examples of applications are given pertaining to multi-degree-of-freedom systems under both deterministic and stochastic loads.
Crossing Borders: An Online Interdisciplinary Course in Health Informatics for Students From Two Countries.
2017
A cross-countries and interprofessional novel approach for delivering an international interdisciplinary graduate health informatics course online is presented. Included in this discussion are the challenges, lessons learned, and pedagogical recommendations from the experiences of teaching the course. Four professors from three different fields and from three universities collaborated in offering an international health informatics course for an interdisciplinary group of 18 US and seven Norwegian students. Highly motivated students and professors, an online technology infrastructure that supported asynchronously communication and course delivery, the ability to adapt the curriculum to meet…
Application of the Health Action Process Approach to Social Distancing Behavior During COVID‐19
2020
Author(s): Hamilton, Kyra; Smith, Stephanie R; Keech, Jacob J; Moyers, Susette A; Hagger, Martin S | Abstract: BackgroundThis study examined the social cognition determinants of social distancing behavior during the COVID-19 pandemic in samples from Australia and the US guided by the health action process approach (HAPA).MethodsParticipants (Australia: Nn=n495, 50.1% women; US: Nn=n701, 48.9% women) completed HAPA social cognition constructs at an initial time-point (T1), and one week later (T2) self-reported their social distancing behavior.ResultsSingle-indicator structural equation models that excluded and included past behavior exhibited adequate fit with the data. Intention and action …