Solid-State Fluorescence Emission

Miscellaneous PAEs (Table 14). Several other PAEs have been examined with respect to emission. The most interesting ones are PAEs in which pyridine (7). benzimidazole (8) (Table 14. entries 7—9). or bipyridine (9) (Table 14. entry 1) units are separated by alkoxy-substituted diethynylbenzenes or diethynyl-(3-hexylthiophene)s 15. These polymers display high fluorescence, which can be pH dependent. A decrease in pH leads to a bathochromic shift in the emission of the imidazoles 8 and may thus find use in sensory applications. Bipyridine-containing PPE 9 may be useful to detect and connect polymer chains by metal ions in a supramolecular fashion. However, solid-state emission of these materials is mostly not reported. 

Although many fluorescent organic dyes suffer serious concentration quenching in the solid state, novel types of luminophore showing intense solid state emission have developed in recent decades hy taking advantage of the frozen conformation. 

In contrast, the fluorescence of PTPAF lb closely resembles its solution spectrum, with maxima at 428 run (2.90 eV) and 452 nm (2.74 eV), and no peak in the low-energy region. The same is true for the solid state emission spectrum of PBPF (Ic), i.e., another PF polymer with bulky side groups, which shows a peak at 457 nm (2.71 eV, pure blue emission), with no emission in the low-energy region. 

Glow discharge is essentially a simple and efficient way to generate atoms. Long known for its ability to convert solid samples into gas-phase atoms, GD techniques provide ground-state atoms for atomic absorption or atomic fluorescence, excited-state atoms for atomic emission, and ionised atoms for MS [158], Commercial instrumentation has been developed for all these methods, except for GD-AFS and pulsed mode GD. 

The yttrium aluminum garnet crystal, Y3 AI5O12, doped withNd + ions, is a well-known solid state laser material (abbreviated to Nd YAG). If the fluorescence lifetime of the main laser emission is 230 /rs and the quantum efficiency of the corresponding emitting level is 0.9, determine (a) the radiative lifetime and... 

In the previous chapter we have introduced the physical basis of the interpretation of optical spectra of centers in crystals. The main effect of these centers is to introduce new energy levels within the energy gap of the crystal, so that the transitions among these levels produce new optical bands that are not present in the perfect crystal. Due to these absorption and emission bands, centers in crystals are relevant for a variety of applications, such as solid state lasers, amplifiers and phosphors for fluorescent lighting and cathode ray tubes. In this chapter, we will describe the main characteristics of the relevant centers for these applications. 

The fluorescence lifetime of the /2 metastable state of Nd + ions in LaBGeOs (a solid state laser) is 280 /u.s and its quantum efficiency is 0.9. (a) Calculate the radiative and nonradiative rates from this excited state, (b) If the effective phonons responsible for the nonradiative rate have an energy of 1100 cm, use the Dieke diagram to determine the number of emitted effective phonons from the F3/2 excited state, (c) From which three excited states of the Nd + ions in LaBGeOs do you expect the most intense luminescence emissions to be generated ... 

Most of the solid-state lasers employ as active material crystals or glasses doped with rare-earth or actinide ions, because these ions exhibit a large number of relatively sharp fluorescent lines, covering the whole visible and near-infrared spectrum 380) search for new laser materials and investigations of the characteristics of laser emission at different temperatures of the active material and with various pump sources have improved knowledge about the solid state spectra and radiationless transitions in laser media 38i). 

The SeaDog sensor utilized in this work is capable of near real-time detection of low concentrations of explosives in water. The sensor utilizes novel sensing materials originally developed by collaborators at MIT. These materials are fluorescent polymers that are highly emissive when deployed as solid-state thin films. When the polymers interact with nitroaromatic explosives such as TNT, the fluorescence is quenched [3-5], The response of these materials to target analytes... 

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