Emission spectra measurements

Fig. 4.6.3 Bioluminescence emission spectra measured with coelenterazine plus 1 i.M Renilla luciferase in the absence (a) and presence (b) of 1 jlM Renilla GFP. From Lorenz et al., 1991.

Figure 12.4 shows the laser intensity dependence of X-ray emission spectra measured at a pulse duration of 30 fs with C = 5 x 10-6. As the laser intensity increased, the X-ray yields increased in proportion. The Rydberg He-like lines from the lsnp-ls2 (n = 3-6) transitions and the dielectronic satellites from the 1 Is2 transition were especially enhanced, which shows that highly excited states of He-like Ar ions were produced due to intensive ion-election collisions. 

Fig. 12.4. The laser intensity dependence of X-ray emission spectra measured with a pulse duration of 30 fs and a contrast ratio of C = 5 x 10 6 1.2 x 1019 W/cm2...

Fig. 12.5. The cluster size dependence of X-ray emission spectra measured at an intensity of 3 x 1018 W/cm2, a pulse duration of 30 fs, and a laser contrast of 4 X 10" Ar = 60 bar (top curve) At = 50 bar (middle curve) Ar = 40 bar (bottom curve)...

Figure 13-15. Emission spectra measured at various angles from the surface normal of a microcavity OLED. The solid line is the noncavity spectrum measured at 0° from an OLED on the same substrate. Reproduced with permission from [161].

Robbins et al. on tryptophan and 3-methylindole since powerful solid-state laser excitation was used. Jameson and Weber have resolved the fluorescence of tryptophan by phase and modulation fluorometry in terms of emission from the zwitterion and anion present in amounts determined by the pH of the solution. The forms interconvert more slowly than fluorescence processes and have similar absorption and emission spectra. Measurements were made with excitation frequencies of 6, 18, and 30 MHz in the pH range 8—10, in which the relative zwitterion concentration varies from 0.82—0.09. Resolved lifetimes were 3.1 0.4 ns for the zwitterion and 8.7 0.1 ns for the anion. The agreement with Gudgin et al. seems satisfactory. 

Hydrogen atom emission spectra measured from the solar corona indicated that the 4s orbital was 102823.8530211 cm , and 3s orbital 97492.221701 cm , respectively, above the Is ground state. (These energies have tiny uncertainties, and can be treated as exact numbers for the sake of this problem.) Calculate the difference in energy (J) between these levels on the basis of these data, and compare this difference to that... 

Emission spectra measured using echelle spectrometer for the discharge ignited in Ar/C2H2 as well as in Ar/CH4 mixtures at different regions along the axis of tube indicates similar pattern. Measured spectra show characteristic emissions for the active sjjecies tike C, C2, CH, etc. which indicates the dissociation of precursors, and participation of hydrocarbon radicals in film deposition (figure 5). 

Figure 6.4 presents examples of the A1 plasma emission spectra measured in backward direction, such as regular plasma emission (Fig. 6.4a), plasma plume emission pumped at 257.5 nm (Fig. 6.4b) and plasma plume emission placed in optical resonator (Fig. 6.4c). Solid curve is regular LIBS, dash curves presents the excitation at 257.5 nm and dot curve presents the excitation at 256.8. All results are measured 4 ps after plasma plume creation, 0 ns acquisition delay and with gate width of 1 ps. Plasma emission lines Full Width at Half Maxima (FWHM) is about...

Fig. 8.28 (a-c) KCl (a) and NCI (b) plasma. Solid curves are absorption spectra Dashed curves are emission spectra measured. Calibration curve for K contents in NaCl measured using absorption spectroscopy (c)... 

In alcohols, the solvation times agree remarkably with the reorientation times of the free alcohol molecules see below, Section 5.3.3. In non-polar solvents, other secondary-sphere solvent molecules may quickly undergo considerable polarisation, as is shown by the difference between optical-absorption and fluorescence-emission spectra measured a few picoseconds after initiation these spectra show maxima at different wavelengths (the Stokes shift ), which can be accounted for by electrostatic models. See Section 6.3.4 below, and G.R. Fleming, Chemical Applications of Ultrafast Spectroscopy, Clarendon Press, Oxford, 1986, pp. 166, seq. 

Fig. 5A-C Nonlinear emission spectra measured from A the cell wall of a parenchyma in maize Zea mays) stem B the stone cell of a pear Pyrus serotina R.) fruit C potato Solarium tuberosum L.) starch granule. These spectra were recorded under similar illumination intensity, with normalized 0.1 s integration time. Note the extraordinarily strong SHG from the starch granule...

Fig. 8. The fluorescence emission spectra (Al) of binary solvent (A2 - normalized curves) (IL4), [Cs-Cilm] [BF4] + DMF) the fluorescence emission spectra (Bl) of all-frfl s P-carotene (B2 - normalized curves) 5 pmol in binary solvent and (Cl) the pure (corrected for fluorescence of ionic liquid) (C2 - normalized curves) fluorescence emission spectra (measured in the 10% step) of all-trans P-carotene in binary solvent mixture with different concentrations of RTIL (DMF signal is at the zero level), respectively X.ex = 413 ntn p.-cuvette.

This having been said, it would be wrong not to mention some remarkable work that has been done by a number of workers who have measured emission spectra of the upper atmosphere and stratosphere. The pressure of the gases that contribute to these spectra (and hence the width of the rotational lines) can vary by over an order of magnitude. By fitting emission spectra measured at very high resolution, workers have been able to derive the concentration profiles of trace constituents in the stratosphere as a function of the distance from Earth s surface. 

In practice, the quantum yield is generally determined by comparing the emission spectmm of the examined luminophore with that of a suitably selected standard, both recorded under the same instrumental conditions (excitation wavelength, excitation and emission slits, detector settings, etc.). The comparison involves the emission intensities of the two species (sample and reference) integrated over the whole wavelength range, that is, the areas underneath the respective emission spectra, measured from the baseline. 

The obvious question is whether both compounds, [RuCbpylj] " and [Ru(i-biq)2(bpy)], exhibit nearly the same spectroscopic properties, as is expected for a localized excitation in [Ru(bpy)3] or whether one observes a distinctly dissimilar behavior. Emission spectra measured above 80 K did not reveal any clear difference [245]. However, it cannot be excluded that crucial effects are smeared out at this relatively high temperature, where only broad bands can be recorded. Indeed, this is the case for the very characteristic values of zero-field splittings (zfs) into the low-lying triplet sublevels [248]. 

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