Far-red fluorescent proteins are required for deep-tissue and whole-animal imaging and multicolor labeling in the red wavelength range, as well as probes excitable with standard red lasers in flow cytometry and fluorescence microscopy. Rapidly evolving superresolution microscopy based on the stimulated emission depletion approach also demands genetically encoded monomeric probes to tag intracel...

When organic or inorganic specimens absorb and subsequently reradiate light, the process is typically a result of fluorescence or phosphorescence. Fluorescence emission is nearly simultaneous with the absorption of the excitation light as the time delay between photon absorption and emission is typically less than a microsecond. When the emission persists long after the excitation light is exti...

The relaxation of electronically excited atomic manganese isolated in solid rare gas matrices is observed from recorded emission spectra, to be strongly site specific. z 6P state excitation of Mn atoms isolated in the red absorption site in Ar and Kr produces narrow a 4D and a 6D state emissions while blue-site excitation produces z 6P state fluorescence and broadened a 4D and a 6D emissions. M...

We report fluorescence imaging of single dye molecules on a glass substrate by two-photon excitation with femtosecond pulses from a mode-locked Ti:sapphire laser. The single-molecule images exhibit a high signal to background ratio (>30:1) and a high spatial resolution (fwhm < /3). A quadratic intensity dependence of single-molecule emission rate is experimentally verified, and single-molecule ...

A focus of research in cell physiology is the detection of Ca 2+ , NADH, FAD, ATPase activity or membrane potential, only to name a few, in muscle tissues. In this work, we report on a biofluorometer using ultraviolet light emitting diodes (UV-LEDs), optical fibers and two photomultipliers (PMTs) using synchronized fluorescence detection with integrated background correction to detect free calc...

Several phycobiliproteins were prepared chromatographically pure and their absorption, fluorescence-emission, fluorescence-excitation and fluorescence-excitation polarization spectra determined. Changes in these spectra with ionic strength of the aqueous medium and chromoprotein concentration were interpreted in terms of interchromophore energy transfer and protein subunit equilibria. The compl...

We report the synthesis and photophysical properties of silver-nanoclusters templated on DNA, with fluorescence excitation and emission at distinct wavelengths that are tuned to common laser excitation wavelengths.

Fluorescence molecular imaging/tomography may play an important future role in preclinical research and clinical diagnostics. Time-and frequency-domain fluorescence imaging can acquire more measurement information than the continuous wave (CW) counterpart, improving the image quality of fluorescence molecular tomography. Although diffusion approximation (DA) theory has been extensively applied ...

Fluorescence measurements are easily made with the aid of a cryogenic fiber optic probe. Emission wavelength time matrixes, excitation emission matrixes, and time-resolved excitation emission matrixes are rapidly collected with a pulsed tunable dye laser, a spectrograph, and an intensified charged-coupled device. Compound identification is based on spectral and lifetime information. The potenti...

The absorption and fluorescence characteristics of subchloroplast particles highly enriched in P700 (1 P700 to 10-15 chlorophyll a molecules) and of two artificial systems are presented here. The fluorescence characteristics measured were excitation and emission spectra, and the degree of polarization of fluorescence. The model systems studied were chlorophyll a and pheophytin a in a polystyren...