Fluorescence spectroscopy excited states

Figure 4.13 pH-Titration of protein Hsp47 monitored by intrinsic tryptophan fluorescence spectroscopy (excitation 295 nm). Data is also indicative of a two stage transition between an Alkali stable state and an Acid stable state via a transient intermediate state (see Fig. 4.8). Fluorescence spectroscopy also reveals that Hsp47 will undergo reversible pFI-driven trans-conformational changes (see Chapter 7) (Reproduced from Momma et al., 2008). /em(iC) is fluorescence emission intensity.

In this study, we adopted two kinds of fluorescence spectroscopy, steady-state and the time-resolved spectroscopy in the picosecond time range, for the analysis of energy flow in whole cells of the marine dinoflagellate Protogonyalux tamarensis under the excitation condition of peridinin. Results show unique fluorescence components in this species and characteristic energy flow among them. 

Teuchner, K., Stiel, H., Leupold, D., Scherz, A., Noy, D., Simonin, 1., Hartwich, G., and Scheer, H., Fluorescence and excited state absorption in modified pigments of bacterial photosynthesis a comparative study of metal-substituted bacteriochlorophylls a, /. Luminesc., 72-74, 612,1997. Fleming, G.R. and van GrondeUe, R., Femtosecond spectroscopy of photosynthetic hght-harvesting systems, Curr. Opinion in Struct. Biol, 1, 738, 1997. 

Mosshauer effect The resonance fluorescence by y-radiation of an atomic nucleus, returning from an excited state to the ground state. The resonance energy is characteristic of the chemical environment of the nucleus and Mossbauer spectroscopy may be used to yield information about this chemical environment. Used particularly in the study of Fe. Sn and Sb compounds. 

Hydrogen transfer in excited electronic states is being intensively studied with time-resolved spectroscopy. A typical scheme of electronic terms is shown in fig. 46. A vertical optical transition, induced by a picosecond laser pulse, populates the initial well of the excited Si state. The reverse optical transition, observed as the fluorescence band Fj, is accompanied by proton transfer to the second well with lower energy. This transfer is registered as the appearance of another fluorescence band, F2, with a large anti-Stokes shift. The rate constant is inferred from the time dependence of the relative intensities of these bands in dual fluorescence. The experimental data obtained by this method have been reviewed by Barbara et al. [1989]. We only quote the example of hydrogen transfer in the excited state of... 

Discussion of topics corresponding to proton transfer occurring in the excited state are included under Fluorescence Spectroscopy and Excited... 

VIIL Fluorescence Spectroscopy and Excited State Proton Transfer... 

Techniques other than UV-visible spectroscopy have been used in matrix-isolation studies of Ag see, for example, some early ESR studies by Kasai and McLeod 56). The fluorescence spectra of Ag atoms isolated in noble-gas matrices have been recorded (76,147), and found to show large Stokes shifts when optically excited via a Si j — atomic transition which is threefold split in the matrix by spin-orbit and vibronic interactions. The large Stokes shifts may be explained in terms of an excited state silver atom-matrix cage complex in this... 

The use of emission (fluorescence and phosphorescence) as welt as absorption spectroscopy. From these spectra the presence of as well as the energy and lifetime of singlet and triplet excited states can often be calculated. 

Wolfbeis, O. S. Fiierlinger, E. pH-dependent fluorescence spectroscopy. 15. Detection of an unusual excited-state species of 3-hydroxyxanthone. J. Am. Chem. Soc. 1982, 104, 4069 1072. 

Upon absorption of UV radiation from sunlight the bases can proceed through photochemical reactions that can lead to photodamage in the nucleic acids. Photochemical reactions do occur in the bases, with thymidine dimerization being a primary result, but at low rates. The bases are quite stable to photochemical damage, having efficient ways to dissipate the harmful electronic energy, as indicated by their ultrashort excited state lifetimes. It had been known for years that the excited states were short lived, and that fluorescence quantum yields are very low for all bases [4, 81, 82], Femtosecond laser spectroscopy has, in recent years, enabled a much... 

Sharonov A, Gustavsson T, Carre V, Renault E, Markovitsi D (2003) Cytosine excited state dynamics studied by femtosecond absorption and fluorescence spectroscopy. ChemPhys Lett 380 173-180... 

Onidas D, Gustavsson T, Lazzarotto E, Markovitsi D (2007) Fluorescence of the DNA double helix (dA)20-(dT)20 studied by femtosecond spectroscopy effect of the duplex size on the properties of the excited states. J Phys Chem Bill 9644-9650... 

Several characteristics of the metal beam have been studied in detail. It is well known that metal clusters and metal oxides are formed as a result of the ablation process. However, these potentially interfering species have been studied in detail130 and it has been concluded that they do not introduce any doubt as to the validity of the experimental results. Much more important than cluster or oxide formation are the atomic electronic state populations of the metal beams. For each metal reactant, these have been characterized using laser-induced fluorescence (LIF) excitation spectroscopy. For Y, only the two spin-orbit states of the ground electronic state (a Dz/2 and a D-3,/2) were observed.123... 

Tomin VI, Tomin VI, Jaworski R (2008) Investigation of reactions from the highest excited states of molecules by fluorescent spectroscopy methods. Opt Spectros 104 40-49... 

Lossau H, Rummer A, Heinecke R, Pollinger-Dammer F, Kompa C, Bieser G, Jonsson T, Silva CM, Yang MM, Youvan DC, Michel-Beyerle ME (1996) Time-resolved spectroscopy of wild-type and mutant green fluorescent proteins reveals excited state deprotonation consistent with fluorophore-protein interactions. Chem Phys 213 1-16... 

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