Figure 30. Photoluminescence and photoluminescence excitation spectra of bulk (solid lines) and nanocrystalline (dashed lines) ZnS:Mn. [Used with permission of American Physical Society, from Bhargava et al. (1994) , Physical Review Letters, Vol. 72, Fig. 1, p. 4162.]

Figure 16. a) For below-band gap photoluminescence, the energy of the incoming photon (hn i ) is enough to excite an electron from a defect’s ground state (GS) to its excited state (ES): the defect subsequently emits a lower-energy photon (hn e ). b) For cathodoluminescence, a high-energy

Figure 40. Photoluminescence spectroscopy reveals that unstable defects are removed by HPHT treatment of Type IIa brown diamonds to decolorize them. In addition, the NV – /NV 0 ratio increases to >1 in treated diamonds (as measured with PL using a 514 nm laser). The H2 defect is rare

Figure 42. Photoluminescence spectra for as-grown ( bottom ) and HPHT annealed ( top ) CVD diamonds collected using 514 nm laser excitation at 77 K. Nitrogen-vacancy and silicon-vacancy centers are observed for both. SiV – is often detected for CVD diamonds, yet extremely rare for natural

Fig. 9. Excitation spectrum of photoluminescence monitored at 625 nm (16,000 cm –1 ) at 77 K.

Fig. 8. Photoluminescence spectrum of sapozhnikovite excited by 405 nm (24,690 cm –1 ) radiation at 77 K.

, the absorbance at 3.0 eV is a result of absorption by both X & Y defects, while at 2.7 eV only defect Y contributes to the spectrum. Using sub-band gap excitation, photoluminescence can be excited from multiple defect centers selectively. A sub-band gap laser incident on a crystal containing multiple defects

Fig. 3 Parallel polarized Raman spectra of E2335 titanite measured on heating from R T to 800 K. The signals near 1045, 1090, and 1180 cm −1 are photoluminescence peaks. The band near 880 cm −1 results from overlapping Raman and photoluminescence signals.

Fig. 14. Photoluminescence (PL) spectrum for diamond U-331/112, T = 800 K ( A ); a fragment of the PL spectrum with details of fine structure ( B ). 1 , 2 , yellow ( 1 ) and green ( 2 ) photoluminescence for the samples U-331/112 and U-331/113, respectively; 3 , differential spectrum.

Figure 6. Photoluminescence (PL) spectra of microdiamonds and high-pressure–high-temperature (HPHT) synthetic diamond grit. (A) Excited with 514 nm laser at liquid nitrogen temperature (LNT), showing nitrogen-vacancy (NV) centers and phonon sidebands. (B) PL spectra excited by 830 nm laser at LNT

Fig. 1 A typical photoluminescence (PL) spectrum of small diamond crystals isolated from high-temperature olivine showing the presence of a strong N3 (415 nm) system as a main feature; the 490.7 nm, H3 (503.2 nm) and H4 (496.2 nm) centers occurred in some stones of this suite, but at much lower

Fig. 4 Photoluminescence spectrum typical of diamonds sized 1.5–2.0 mm: the 490.7 nm system is dominant indicating the presence of plastic deformation in the stones.

Fig. 8. Spatial distribution of photoluminescence in natural diamonds with cloudy microinclusions (samples MS-1, MS-3, and MS-8). The images were obtained by excitation using laser with wavelengths of 405 and 532 nm. a – f , See explanations in the text.

Characteristic photoluminescence spectra for different genetic zones of the studied diamonds: a , Cubic cores of diamonds with a transition zone; b , cubic cores of diamonds with a sharp cuboid–octahedron transition; c , cube–octahedron transition zone; d , rim of diamonds with a transition