Quantum single molecule

The vast majority of single-molecule optical experiments employ one-photon excited spontaneous fluorescence as the spectroscopic observable because of its relative simplicity and inlierently high sensitivity. Many molecules fluoresce with quantum yields near unity, and spontaneous fluorescence lifetimes for chromophores with large oscillator strengths are a few nanoseconds, implying that with a sufficiently intense excitation source a single... 

Finally, tlie ability to optically address single molecules is enabling some beautiful experiments in quantum optics. The non-Poissonian photon arrival time distributions expected tlieoretically for single molecules have been observed directly, botli antibunching at short times [112] and bunching on longer time scales [6, 112 and 113]. The fluorescence excitation spectra of single molecules bound to spherical microcavities have been examined as a probe... 

Plakhotnik T, Walser D, Pirotta M, Renn A and Wild U P 1996 Nonlinear spectroscopy on a single quantum system two-photon absorption of a single molecule Science 271 1703-5... 

Basche T, Kummer S and Brauchle C 1995 Direct spectroscopic observation of quantum ]umps of a single molecule Nature 373 132-4... 

It is always possible to convert internal to Cartesian coordinates and vice versa. However, one coordinate system is usually preferred for a given application. Internal coordinates can usefully describe the relationship between the atoms in a single molecule, but Cartesian coordinates may be more appropriate when describing a collection of discrete molecules. Internal coordinates are commonly used as input to quantum mechanics programs, whereas calculations using molecular mechanics are usually done in Cartesian coordinates. The total number of coordinates that must be specified in the internal coordinate system is six fewer... 

The algorithms of the mixed classical-quantum model used in HyperChem are different for semi-empirical and ab mi/io methods. The semi-empirical methods in HyperChem treat boundary atoms (atoms that are used to terminate a subset quantum mechanical region inside a single molecule) as specially parameterized pseudofluorine atoms. However, HyperChem will not carry on mixed model calculations, using ab initio quantum mechanical methods, if there are any boundary atoms in the molecular system. Thus, if you would like to compute a wavefunction for only a portion of a molecular system using ab initio methods, you must select single or multiple isolated molecules as your selected quantum mechanical region, without any boundary atoms. 

The key feature in statistical mechanics is the partition function Just as the wave function is the corner-stone of quantum mechanics (from that everything else can be calculated by applying proper operators), the partition function allows calculation of alt macroscopic functions in statistical mechanics. The partition function for a single molecule is usually denoted q and defined as a sum of exponential terms involving all possible quantum energy states Q is the partition function for N molecules. 

The processes by which unsaturated monomers are converted to polymers of high molecular weight exhibit the characteristics of typical chain reactions. They are readily susceptible to catalysis, photoactivation, and inhibition. The quantum yield in a photoactivated polymerization in the liquid phase may be of the order of 10 or more, expressed as the number of monomer molecules polymerized per quantum absorbed. The efficiency of certain inhibitors is of a similar magnitude, thousands of monomer molecules being prevented from polymerizing by a single molecule of the inhibitor. ... 

According to this partisan view of the evolution of theoretical chemistry we draw the impression of a choice, in which the single molecules represent the basic unit of investigation, the quantum theory provide the theoretical basis, and computer calculations the final step. The three periods of growth are, in reality related, and the " sudden" changes in between do not corresponds to "revolutions" in according to the meaning this word has in the Kuhn s analysis [4]. 

Mclnnes EJL (2006) Spectroscopy of Single-Molecule Magnets. 122 69-102 Merunka D, Rakvin B (2007) Anharmonic and Quantum Effects in KDP-Type Ferroelectrics Modified Strong Dipole-Proton Coupling Model. 124 149-198 Meshri DT, see Singh RP (2007) 125 35-83... 

Hohng, S. and Ha, T. (2005). Single-molecule quantum-dot fluorescence resonance energy transfer. Chemphyschem 6, 956-60. 

J., Zueco, D. and Luis, F. (2013) Coupling single molecule magnets to quantum circuits. New J. Phys., 15, 095007. 

M., Brechin, E.K. and Dressel, M. (2008) Direct observation of quantum coherence in single-molecule magnets. Phys. Rev. Lett., 101, 147203. 

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