Photoluminescence excitation spectra

Monemar, B. Fundamental energy gap of GaN from photoluminescence excitation spectra. Phys. Rev. 1974, BIO, 676. 

The absence of an absorption cross section for the exciplex means that it cannot be excited optically. Instead, an exciplex is formed by complexation of a ground-state molecule with an excited-state molecule, i.e. by Dexter-type energy transfer from a bulk exciton. Figure 2.10 plots the photoluminescence excitation spectra of the PFB, the F8BT, and the exciplex emission, all measured from the same 50 50 PFB F8BT blend. The PLE signature of the exciplex is a superposition of those of the two excitons. Hence, the exciplex is excited via energy transfer from the two bulk excitons. 

Fig. 2.10 Photoluminescence excitation spectra of a PFB F8BT blend. The detection wavelengths are 465 nm (black), 540 nm (red), and 600 nm (green), corresponding to the PFB and F8BT exciton emissions and the exciplex emission, respectively. The exciplex spectrum resembles a superposition ofthe two exciton spectra, pointing towards indirect excitation of the exciplex via transfer from the excitons. The spectra were taken using a SpexNova spectrofluorimeter and are not corrected for the spectral response.

Figure 1. Photoluminescence emission spectra (PL) and photoluminescence excitation spectra (PLE) of CdSiMn nanocrystals embedded in a polymer film.

Fig. 8. Photoluminescence excitation spectra of the stereoregular phenylcyclosiloxanes [PhSiO(OSiMc3)] where n = 4, 6, 8, and 12, together with the tetraphenyl-l,3-disiloxanediol, measured as solids (powder) at liquid nitrogen temperature, 7 = 77 K. Emission wavelength A = 505 nm, speetral bandwidth AA = I nm, edge filter (50% transmission at 495 nm). Legend D2 tetraphenyidisiloxanediol D4-DI2 - phenyleyelo-siloxane, ring sizes of n = 4-12.

Xex = 276, 367, 395, and 460 nm for emission). The inset represents the concentration dependence of the emission intensity of Caio xEu,t(Si207)3Q2(7.ex = 395 nm). Reprinted from Ref. [20], Copyright 2006, with permission from Elsevier, b Photoluminescence excitation spectra ((a) T-em = 585 nm) and emission spectium ((b) Xex = 395 nm) of Ca5(Si04)2Cl2 Eu. Reprinted from Ref. [21], Copyright 2006, with pamission from Elsevier... 

Figure 6. Photoluminescence excitation spectra of the stereoregular phenylcyclo-siloxanes, [PhSi(0SiMe3)0], n = 4, 6, 8, 12, together with the linear tetraphenyl-1,3-siloxanediol, measured (in powder form), at the temperature of liquid nitrogen, T = 77 K. Emission wavelength 505 nm, spectral bandwidth ca. 1 nm. D2 linear D4 n=4 D6 n=6 D8 =8 D12 n= 2.

Fig. 2 Photoluminescence and photoluminescence excitation spectra of Eu complex-capped ZnSe hybrid QDs synthesised from (a) Eu acetate hydrate, (b) Eu acetylacetonate hydrate and (c) CIE colour coordinates and images of ZnSe QDs (1), Eu-complexes (2) and Eu complex-capped ZnSe QDs (3). Reproduced with permission from reference 9. Copyright The Royal Society of Chemistry 2011.

Figure 9-12. Absorption (Abs), photoluminescence excitation spectrum (PLCX), pholo-lumincscence (PL), and electroluminescence (EL) emission of mLPPP.

Figure 5. Triboluminescence Spectrum of Uranyl Nitrate Hexa-hydrate. The photoluminescence excitation spectrum is shown for comparison the photoluminescence emission has been...

The action spectrum of the photocatalytic isomerization reactions on MgO, defined as the plot of the reaction rate vs the wavelength of the light used, shows a good agreement with the absorption spectrum, i.e., the photoluminescence excitation spectrum of the MgO (96-98, 248). The addition of O2 or CO to MgO led to the quenching of the photoluminescence. Similarly, the rates of the photocatalytic isomerization reactions on MgO were easily inhibited by the addition of CO. its extent increasing with an increase in CO pressure. 

Fig. 9.8 Photoluminescence excitation spectrum of a quantum well structure with parabolic potential barriers. (After ref. [85])...

Figure 30.4 Spectra obtained for (20 mol %) containing diureasil (d-U2000-Er(CIO)4). (a) Photoluminescence spectrum obtained under 350 nm excitation. Er absorption lines are shown in the figure. Inset Photoluminescence excitation spectrum (emission monitored at...

Figure 1. Photoluminescence emission and excitation spectrum for benitoite showing Ti + luminescence.

The candoluminescent and radical recombination spectra of willemite are shown in comparison with the UV-excited spectrum in Figure 10. The envelope of the main emission band at 530 nm is the same in all spectra but the radical recombination excitation brings out another feature at 613 to 642 nm not seen in the photoluminescence spectrum. Similar behavior is seen in other Mn2+ activated candoluminescent spectra (20)... 

Photoluminescence excitation spectroscopy (PLE) is generally used to identify the excited-state structure in quantum wells. For GalnN/GaN quantum wells, Im et al [14] used PLE to study single wells of various widths. Similarly to the results from absorption, electro-absorption, and electroreflectance measurements, a large Stokes shift of the onset of the PLE spectrum with respect to the dominating photoluminescence peak was observed at low temperature [14]. 

Figure 26 Emission spectra (PL, EL) in PC at room temperature of 40 wt% TPD donor solution with a 40 wt% of PBD acceptor added. The photoluminescence (PL) spectrum excited at 360 nm, the electroluminescence (EL) spectra (I, II) originate from the recombination radiation in a 60 nm thick film, taken at two different voltages. Absorption (Abs) and PL spectra (excitation at 360 nm) of (75wt% TPD 25wt% PC) and (75wt% PBD 25wt% PC) spin-cast films are given for comparison. Molecular structures of the compounds used are given in the upper part of the figure TPD [N,Nf-diphenyl-A v/V/-bis(3-methylphenyl)-l,l -biphenyl-4,4 diamine PBD [2-(4-biphenyl)-5-(4- er .-butylphenyl)l,3,4-oxadiazole PC[bisphe-nol-A-polycarbonate]. Adapted from Ref. 112.

The Ps 2 Na fluorescence varies with laser frequency, producing a series of fluctuation bands extending from 17500 to 19700 cm Figure 7 presents the continuation of the spectra in Figure 6 in order, an excitation spectrum dominated by the Na2 B-X system, P3/2 laser induced atomic fluorescence, Pi/2 fluorescence, and appropriate photoluminescence spectra which at higher frequencies correspond in large part to the B-X system. 

Figure 7. Continuation of spectra presented in Fig. 6. Key a, excitation spectrum (Ar ion pumped coumarin 7) showing Na B n — AT 2/ fluorescence b, Ps/i Na laser induced atomic fluorescence c, Pi/i laser induced atomic fluorescence and d, Fast photoluminescence scans indicating relative magnitudes of Na D-line and Noi B-X fluorescence (tick marks indicate v = 17,000 and 21,000 cm and indicates laser excitation frequency.

Figure 2.20 Photoluminescence spectra of SrO recorded at 300K before and after pyridine (Py) adsorption, (a) emission spectrum of SrO (b) excitation spectrum of SrO (c) emission spectrum after Py adsorption (d) excitation spectrum after Py adsorption. Reprinted from ref [88], with permission from the Royal Society of Chemistry.

On the other hand, in the excitation spectrum, the emission intensity 4, at the monitored emission band, is plotted as a function of the wavelength A of the excitation light, w hich varies as the extinction coefficient of the absorbing molecules. Therefore, the excitation spectrum exhibits the same spectral appearance as that of the absorption spectrum. The advantage of measuring the excitation spectrum in addition to the emission spectrum is the greater sensitivity even for low concentrations of photoluminescent material compared to standard absorption measurements. 

Figure 19 shows the typical photoluminescencc spectrum of the anchored vanadium oxide catalyst prepared by photo-CVD methods (a), its corresponding excitation spectrum (b), and the UV absorption spectrum of the catalyst (c) (56,115,116). These absorption and photoluminescence spectra (phosphorescence) are attributed to the following charge-transfer processes on the surface vanadyl group (V=0) of the tetrahedrally coordinated VO4 species involving an electron transfer from to V and a reverse radia-... 

Fig. 26. Photoluminescence spectra of the molybdenum oxide catalyst anchored to Si02 (molybdenum oxide/Si02) at 77 K (a) and at 298 K (b) and their excitation spectrum. Excitation wavelength at 280 nm emission monitored at 520 nm [reproduced with permission from Anpo...

Fig. 29. Photoluminescence spectrum and its excitation spectrum at 77 K of titanium oxide anchored onto porous Vycor glass. (Excitation wavelength and its slit width were 280 nm and 10 nm, respectively. Emission slit width was 10 nm.) The anchored catalyst was degassed at 423 K and anatase Ti02 powder was degassed at 573 K.

Upon adsorption of benzophenone on oxides with strongly acidic properties, the phosphorescence spectrum exhibits a structureless band with a Atnax at about 490 nm in addition to the normal phosphorescence of benzophenone. The A max of the excitation spectrum of this band was observed at approximately 380 nm, and its intensity increased in the order of the aluminosilicate, H-mordenite, and HY zeolite. In the spectrum of HY zeolite containing benzophenone, only one structureless phosphorescence band could be observed. A similar phosphorescence band could be observed for benzophenone dissolved in CHCI3, which also involves dry HCl. We can therefore assign phosphorescence at about 490 nm to the protonated form ofbenzophenone. These findings correspond with studies of the photoluminescence of benzophenone dissolved in various concentrated acidic solutions (277). Consequently, since the presence of a phosphorescence spectrum at about 490 nm with benzophenone adsorbed on the aluminosilicate, H-mordenite, or HY zeolite is associated with the presence of the protonated form of benzophenone, the data indicate the existence of proton-donor centers on these oxides with acid strengths < for benzophenone (about 5.6) (216). On HY zeolite, almost all the adsorbed benzophenone changes into protonated benzophenone. On aluminosilicate surfaces, the relative intensities of the phosphorescence spectra attributed to the protonated and unprotonated forms are approximately the same. 

Fig. 55. Phololumiiiescence (a) and its excitation spectrum (b) of Cu(I)ZSM-5 aitalysl and the effect of CO addition on the photolumincscencc (1-4). Catalyst was prepared by evacuation of the original Cu(II)ZSM-5 sample (1.9 wt% as Cu metal) at 973 K. Addition of CO was carried out at 77 K. CO pressure (Pa) 1, 173 2, 306 3 and 3 (excitation spectrum of the photoluminescence spectrum 3), 372 4, 2660 [reproduced with permission from Yania-shita et al. (7iSd)].

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