Two-line fluorescence

Bradshaw, et al. (28). in their experiments, a continuum light source was used although they have since used pulsed laser sources. We have also performed some preliminary experiments (29). The result of these experiments show the necessity of using laser excitation sources if there is to be adequate signal noise to perform measurements in turbulent flows. We are currently assembling a CW laser system for two-line fluorescence in our laboratory. 

Bradshaw, J. Bower, J. Weeks, J. Johnson, D. J. Winefordner, J. D. "Application of the Two Line Fluorescence Technique to the Temporal Measurement of Small Volume Flame Temperature" 10th Material Research Symposium on Characterization of High Temperature Vapors and Gases, NBS, Gaithersburg, Maryland, 18-22 September, 1978. 

Fig. 6 Normalized linear absorption (solid black line), anisotropy (blue circles), and corresponding 2PA spectrum measured by two-photon fluorescence (red squares) and Z-scan (green circles) for SD 2405. Molecular structure is shown to the left...

Marose S., Lindemann C., Scheper T., Two-Dimensional Fluorescence Spectroscopy A New Tool for On-Line Bioprocess Monitoring, Biotechnol. Prog., 1998 14 63-74. 

The characteristic K line consists of a closely spaced doublet with a 2 1 intensity ratio between the K i and K 2 lines. This not a problem if a low spatial resolution recording medium, such as a fluorescent screen and image intensifier, is used but is a problem if high resolution nuclear emulsion plates are used. Then individual dislocation images are doubled because the diffracted beams from the two lines make different directiorrs in space, giving rise to a type... 

Guild, J. B., and Webb, W. W. 1995. Line scanning microscopy with two-photon fluorescence excitation. Biophys. J. 68 290a. 

Other methods, based upon two lines, may be used. Two-line methods may be used in absorption, emission or fluorescence. The signal is... 

Fig. 33 Two-photon fluorescent images of photosensitive films developed (via 350-nm broadband exposure, 4.4mW/cm ) using an Air Force resolution target mask, a Image recorded by channel 1, b image recorded by channel 2, and c fluorescence intensity by scanning an xy line across one set of three-membered elements (line across set 5)...

Pitz, R. W. Daily, J. D. "Measurement of Temperature in a Premixed Methane-Air Flame by Two-Line Atomic Fluorescence" Western States Section/The Combustion Institute Spring Meeting, 1977. 

Fig. 9.11 Two-dimensional fluorescence spectra of E. coli holo-(A) and apotryptophanase (B) in 100 mM potassium phosphate, pH 7.8. Fluorescence spectra were measured at 5-nm intervals of excitation wavelength and represented in contour. The two cross lines at the upper left-hand and lower right-hand comers in maps were due to primary and secondary scattering, respectively. Source Ref. 18...

Figure 14.8 shows the plot of Trp to heme distance obtained by fluorescence energy transfer as a function of tc2 (from 0 to 4) for the two shortest fluorescence lifetimes (solid curve). The five dotted lines in the figure show the crystallographic distances between tryptophan residues and heme. The intersection between the crystallographic lines and the energy-transfer plots is equal to the tc2 corresponding to the specific tryptophan. 

Schiigerl K, Lindemann C, Marose S, Scheper T (1998) Two-dimensional fluorescence spectroscopy for on-line bioprocess monitoring. In Berovic (ed) Bioprocess Engineering Course. Supetar, Croatia, Natl Inst of Chem, pp 400-415... 

Apart from the low-resolution vapor spectrum reported by Glass, Robertson and Merritt 46>, no other study of the second system is available. It is therefore not possible to discuss line shapes in the vapor-phase spectrum in relation to the decay rates of the two-component fluorescence. More information is avEiilable for the crystal, but in the condensed phase the decay rate of the intermediate pressure-dependent fluorescence may have been considerably increased, as is the case for benzophenone. 

An electronic energy-level diagram determined from the laser-induced fluorescence spectrum of 9-hydroxyphenalenone [6] in a neon matrix is shown in Fig. 3. An emission line from the lowest vibrational level in the Si state is found to be split into a doublet. The energy difference between these two lines... 

Thus, in the case of parallel dipole moments the spectrum is composed of two lines of equal band widths ( F) located at frequencies %/ A2 + 21 i2 and there is no the central component in the fluorescence spectrum at the laser frequency a>i. The eigenvalue X = 0 contributes to the coherent scattering of the laser field. When Ti2 = 0, the spectrum is composed of three lines the central line of the bandwidth i T located at the laser frequency and two sidebands of band widths [ ... 

The troubles of excitation scans can be overcome in the two-line approach. Here, only two transitions are probed. But the key point is that the excited molecular level is the same in both excitations that occur in a sequence where one transition is probed while the detection is made for the other transition. In this manner, the spurious dependences on quenching and other molecular parameters are canceled when the ratio between the fluorescence signals at the two distinct emitted wavelengths is measured. 

Marcus etal. (2004) have studied the speciationof Mn, Fe, Zn and As in one of the Baltic Sea concretions described by Hlawatsch et al. (2002) by means of micro X-ray fluorescence, micro X-ray diffraction and micro X-ray spectroscopy. The concretion was shown to consist of thin, alternating Fe- and Mn-rich layers. The Fe-rich layers consisted of two-line ferrihydrite in which As was mostly pentavalent and the Mn-rich layers consisted of birnessite in which Zn is tetrahedrally coordinated and soibed in the interlayers of birnessite. The occurrence of 15% of As(lll) in Fe-rich layers and of-15% Mrf+ in Mn-rich layers was thought to reflect the stagnation of the bottom waters at the time of the deposition of the Fe- and Mn-rich layers. 

Nonresonance Fluorescence. Nonresonance fluorescence occurs when the exciting wavelength and the wavelength of the emitted fluorescence line are different. There are two basic types direct-line fluorescence and stepwise-line fluorescence. 

The strength of a design concept is considerably enhanced if expandability options are available. This is the case with fluorescent PET sensors and we present two lines of development here. First, we show how the addition of targetting and anchoring modules can permit us to use these molecular sensors to examine, and throw light on, problems in the nanometre domain. Second, we expand the fluorescent PET sensor concept beyond its apparent jurisdiction into another spin manifold - into phosphorescent PET sensor construction. 

A recent development has been the use of two-dimensional fluorescence spectroscopy as a new method for on-Hne monitoring of bioprocesses [108]. As ergot alkaloids fluoresce, the formation of the product during cultivation can be observed by two-dimensional fluorescence spectroscopy. Substraction spectra offered on-line real time information about the productivity during the cultivation. It was possible to follow the biomass concentration on-line by monitoring the culture fluorescence intensity in the region of riboflavine and its derivatives. This is a powerful application of this new sensor since the on-Une determination of biomass is extremely complicated for this fimgus. 

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