Internal Stark effect

Electronic excitation of the chromophore is simulated by instantly switching the charges (and in some studies also the geometry) on the QM system to excited state (Sj) values. Most of the internal Stark effect (ISE) is expressed implicitly by the difference of the potentials at different atoms. 

Lockhart DJ, Kim PS (1992) Internal Stark effect measurement of the electric field at the amino terminus of an alpha helix. Science 257 947-951... 

One of the simplest, but most intriguing clusters is synthesized by gas phase deposition and consequent diffusion of sodium atoms into an empty cage [Na3]3+ to give a four sodium atom cluster, [Na4]3+, with an unpaired delocalized electron within the cage (9)/10)/ll)X12). The UV-VIS absorption spectrum of the Na43+sodalite is dominated by an electronic transition between the internal Stark effect broadened ground and first excited state of the Na43+ cluster. EPR studies of this sodalite electride have been discussed previously (10,11,12) however, no quantitative measurements have been previously reported for the optical properties of this phase. 

Drobizhev M, Tillo S, Makarov NS, Hughes TE, Rebane A (2009) Color hues in red fluorescent proteins are due to internal quadratic stark effect. J Phys Chem B 113 12860-12864... 

Although calibrated Stark effects can provide a valuable new way of probing internal electric fields in semiconductors and devices, the theoretical calculation and prediction of these Stark coefficients is as yet at an inadequate stage. Also, while NMR Stark effects upon chemical shifts and exchange (J) couplings have been studied in high-resolution solution NMR, they have not yet been observed in the NMR of semiconductors. 

Significant differences in the optical signatures of Eu3+ ions were observed between GaN Eu QDs and GaN Eu layers (Andreev et al., 2005b) (1) the emission fine at 633.5 was not observed in GaN Eu QDs for unknown reason (2) the 5Do 7F2 transition was red shifted by 1.7 nm in QDs compared to the layer sample, which could be induced by a strong internal electric filed in QDs (quantum confinement Stark effect) (3) the PL intensity is almost temperature independent for GaN Eu QDs, but sensitive to temperature for GaN Eu layers (Hori et al., 2004). 

The aim of this type of investigation has been the better characterization of protein spectra, in terms of their constituent aromatic amino acids, by increasing the degree of resolution of the fine structure of the latter and hence making their identification and differentiation more -certain. This effect of low temperature results from the stabilization of internal Stark and Zeeman effects, which are the chief temperature-sensitive factors determining the frequency spread of absorption bands. Sinsheimer et al. (1950) give a brief review of the subject in relation to organic compounds. 

The next section introduces EA spectroscopy. In a macroscopic description, the EA signal can be viewed as a nonlinear field-induced optical effect. In molecular solids, the microscopic origin of EA can often be ascribed to the Stark effect. The quadratic dependence of EA on the electric field will be derived. Subsequently we will focus on EA as an optical probe of the internal electrostatic fields in organic diodes,... 

Gafeit, J., Friedrich, J., Vanderkooi, J.M., Fidy, J. Structural changes and internal fields in proteins. A hole-burning Stark effect study of horseradish peroxidase. J. Phys. Chem. 99, 5223-5227 (1995)... 

The spontaneous emission of C-plane (In,Ga)N quantum wells is determined by both the electron-hole wavefunctions separation due to the built-in internal electrostatic field (quantum-confined Stark effect) and exciton local-i2ation caused by potential fluctuations [71-74]. The reali2ation of M-plane (In,Ga)N/GaN MQWs allows us to investigate the impact of exciton locali2ation on radiative recombination without the influence of internal electrostatic fields. To study the recombination mechanism of M-plane (In,Ga)N/GaN MQWs, continuous-wave photoluminescence (cw-PL) spectroscopy and time-resolved (TR) PL were carried out. 

However, for polar heterostructures in the III-N system (i.e. for QWs or QDs grown along the [0001] direction of the noncentrosymmetric wurtzite structure), optical properties are usually dominated by the quantum confined Stark effect resulting from the internal field [5]. The confined electrons and... 

GaN band gap owing to the quantum confined Stark effect [4]. This is a first indication that the effects of the internal electric field are reduced compared to polar QDs [19, 43]. The PL spectrum does not evolve as a function of excitation power density over 6 orders of magnitude, which shows that no screening or state filling effects are observed in our CW experiments. 

In contrast to RCs from R. viridis where charge separation is blocked by double reduction of and Q, the membrane bound RC of the Dll mutant could be cast into a PVA film, thus allowing the application of electric fields at low temperatures. Measurements of the steady state fluorescence yield show that the lifetime of P increases by 1.5% in an external electric field of c 710 V/cm. This effect is by a factor of 2 4 larger than the Stark effect measured in the peak of the Qy absorption band of the dimer P. In principle, this field induced decrease of the fluorescence may arise from two sources (i) the increase of the internal conversion rate by mixing in charge transfer states and (ii) a field induced transfer to the inactive B-branch. 

As a consequence of the collective motion of the neutral system across the homogeneous magnetic field, a motional Stark term with a constant electric field arises. This Stark term inherently couples the center of mass and internal degrees of freedom and hence any change of the internal dynamics leaves its fingerprints on the dynamics of the center of mass. In particular the transition from regularity to chaos in the classical dynamics of the internal motion is accompanied in the center of mass motion by a transition from bounded oscillations to an unbounded diffusional motion. Since these observations are based on classical dynamics, it is a priori not clear whether the observed classical diffusion will survive quantization. From both the theoretical as well as experimental point of view a challenging question is therefore whether quantum interference effects will lead to a suppression of the diffusional motion, i.e. to quantum localization, or not. 

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