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1.
Chabazite-Ca deposited on dacite laccolith from Osódi Hill, Dunabogdány, Hungary, exhibited bluish-white luminescence under ultraviolet (UV) light. The photoluminescence (PL) and optical excitation spectra of chabazite-Ca were obtained at 300 K. The PL spectrum under 300-nm excitation consists of (1) a Ce3+ band with a peak at 340 nm, (2) a broad main band with a peak at 453 nm and (3) five narrow bands at 592, 616, 650, 700 and 734 nm due to Eu3+. The main band is spread over the entire visible-wavelength region. The excitation spectrum obtained by monitoring green luminescence at 520 nm consists of a band at wavelengths shorter than 200 nm and an extremely broad band with a peak at 385 nm. The extremely broad band is spread over not only the UV region but also the blue region. The features of PL and excitation spectra suggest that the origin of bluish-white luminescence is luminescent organic matter incorporated into chabazite-Ca crystals during growth.  相似文献   

2.
The photoluminescence (PL) and optical excitation spectra of baratovite in aegirine syenite from Dara-i-Pioz, Tien Shan Mts., Tajikistan and katayamalite in aegirine syenite from Iwagi Islet, Ehime, Japan were obtained at 300 and 80 K. Under short wave (253.7 nm) ultraviolet light, baratovite and katayamalite exhibited bright blue-white luminescence. The PL spectrum of baratovite at 300 K consisted of a wide band with a peak at approximately 406 nm and a full width at half maximum (FWHM) of approximately 6.32k cm−1. The excitation spectrum of the blue-white luminescence from baratovite at 300 K consisted of a prominent band with a peak at approximately 250 nm. The PL and excitation spectra of katayamalite were similar to those of baratovite. The luminescence from these minerals was attributed to the intrinsic luminescence from the TiO6 center.  相似文献   

3.
The photoluminescence (PL) spectra, excitation spectra, and PL decay curves of natural, heat-treated, and γ-ray-irradiated thenardites from Ai-Ding Salt Lake, Xinjiang, China, were studied. The natural thenardite under 300 nm excitation showed milk-white luminescence, and the PL spectrum consisted of an extremely broad band with a peak located at approximately 509 nm, spreading over a wide range of UV and visible wavelengths. The excitation spectra, obtained by monitoring the luminescence at 530 nm, consisted of a broad band with a peak located at approximately 235 nm and a flat band spreading over a wide range of UV and visible wavelengths. The PL decay curve of natural thenardite consisted of a fast-decay component with a lifetime of less than 0.1 μs and a slow-decay component with a half-decay time of approximately 0.4 s. The heat treatment of thenardite at 900°C for 20 min reduced the luminescence efficiency to 1/100. The γ-ray irradiation of thenardite reduced the luminescence efficiency to approximately half.  相似文献   

4.
The photoluminescence and excitation spectra of sodalites from Greenland, Canada and Xinjiang (China) are observed at 300 and 10 K in detail. The features of the emission and excitation spectra of the orange-yellow fluorescence of these sodalites are independent of the locality. The emission spectra at 300 and 10 K consist of a broad band with a series of peaks and a maximum peak at 648 and 645.9 nm, respectively. The excitation spectra obtained by monitoring the orange-yellow fluorescence at 300 and 10 K consist of a main band with a peak at 392 nm. The luminescence efficiency of the heat-treated sodalite from Xinjiang is about seven times as high as that of untreated natural sodalite. The emission spectrum of the S2 − center in sodalite at 10 K consists of a band with a clearly resolved structure with a series of maxima spaced about 560 cm−1 (20–25 nm) apart. Each narrow band at 10 K shows a fine structure consisting of a small peak due to the stretching vibration of the isotopic species of 32S34S−, a main peak due to that of the isotopic species of 32S2 − and five peaks due to phonon sidebands of the main peak.  相似文献   

5.
Baghdadite from Fuka, Okayama Prefecture, Japan shows a bright yellow fluorescence under UV (Hg 253.7 nm) excitation. The photoluminescence (PL) spectrum at 300 K consists of one large band near 580 nm and two small UV bands at 318 and 397 nm. The optical excitation spectrum of the bright yellow fluorescence consists of two bands near 220 and 250 nm. The temperature dependence of the PL intensity exhibits linear thermal quenching. To reveal the origin of the bright yellow fluorescence from baghdadite, powder Ca3(Zr,Ti)Si2O9 crystals are synthesized. Synthetic Ca3(Zr,Ti)Si2O9 shows luminescence spectra similar to those of baghdadite, and the intensity of the yellow fluorescence is markedly increased by titanium addition. The origin of the bright yellow fluorescence from baghdadite is ascribed to the existence of titanium.  相似文献   

6.
The emission and excitation spectra of yellow luminescence due to S2 − in scapolites (#1 from Canada and #2 from an unknown locality) were observed at 300, 80 and 10 K. Emission and excitation bands at 10 K showed vibronic structures with a series of maxima spaced 15–30 and 5–9 nm, respectively. The relative efficiency of yellow luminescence from scapolite #2 was increased up to 117 times by heat treatment at 1,000°C for 2 h in air. The enhancement of yellow luminescence by heat treatment was ascribed to the alteration of SO3 2− and SO4 2− to S2 − in scapolite.  相似文献   

7.
Natural fluorite emitting yellow fluorescence under UV light   总被引：1，自引：0，他引：1  
Many mineralogists believe that fluorite emits violet fluorescence under UV light, but a special fluorite from Japan emits yellow fluorescence under UV light. The analysis by inductively coupled plasma-mass spectrometry (ICP-MS) shows that this fluorite includes high concentrations of Dy together with various rare-earth (RE) impurities other than Pm and Eu. Photoluminescence (PL) emission and excitation spectra of the fluorite are investigated at 10, 80 and 300 K. The origin of yellow fluorescence is attributed to the electronic transition within Dy3+. Profiles of the PL and excitation spectra depend on the excitation wavelength and on the observation wavelength, respectively. The obtained spectra are ascribed to the RE ions Ce3+, Sm3+, Tb3+, Dy3+, Ho3+, Er3+, Sm2+ and Yb2+ in the fluorite. In natural fluorite, the low concentration of Eu enables us to observe the bright fluorescence characteristic of trivalent RE ions, instead of the bluish violet fluorescence due to Eu2+.  相似文献   

8.
The sodalite sample used in this investigation did not exhibit the characteristic orange-yellow luminescence due to the $ {\text{S}}_{ 2}^{ - } $ center, because there was no trace of sulfur impurity. The heat-treated samples exhibited green and red luminescence with maximum intensity at 496 and 687 nm, respectively, under 264 nm excitation at room temperature. Their luminescence intensities were extensively dependent on the treatment temperature. The green luminescence efficiency of the sample heat-treated at 900 °C was 6.5 times higher than that of unheated natural sodalite. At 8.5 K, the green luminescence showed a vibronic structure. After heating at 1,300 °C, the crystal structure of sodalite was transformed to NaAlSiO4 (carnegieite), and the intense red luminescence was exhibited in the NaAlSiO4 sample. The peak wavelength of the red luminescence shifted from 687 nm at 300 K to 726 nm at 8.5 K. The luminescence lifetimes of the green and red luminescence at room temperature were 2.1 and 5.1 ms, respectively. It was proposed that the origin of the green luminescence is Mn2+ replacing Na+, and that of the red luminescence is Fe3+ replacing Al3+ in sodalite or NaAlSiO4 (carnegieite).  相似文献   

9.
Variations in thermoluminescence spectra are reported for four types of geological quartz examined with a new spectrometer featuring dual imaging photon detectors that separately and simultaneously detect (1) uv-blue (200–450 nm) and (2) blue to near infrared (400–800 nm) emission. Samples show striking differences which appear to be characteristic of their geological origin. Volcanic quartz phenocrysts from acid volcanics show red thermoluminescence (TL) emission bands centered at 620–630 nm that are 100 times more intense than similar bands in other quartz, while a violet emission at 420–435 nm was observed exclusively in igneous quartz (volcanic and granitic). A broad emission band centered at 560–580 nm was observed only in quartz formed hydrothermally. Massive quartz from Li-rich pegmatite bodies shows narrow, intense 470 nm emission bands at 230° C apparently related to Al and to Ge defects detected with electron paramagnetic resonance (EPR), and emission bands at 330 and 280 nm, possibly related to recombination at oxygen vacancies. The common 380 nm emission band of quartz was observed in both volcanic and granitic quartz, but was not detected in either the pegmatitic or the hydrothermal vein quartz. Observed spectral variation is identified as a potential source of error in luminescence dating.  相似文献   

10.
The optical luminescence excited with synchrotron radiation along a preferential orientation of a quartz crystal has been investigated. It is found that the crystal is composed of two distinct regions, only one of which luminesces upon X-ray excitation. This luminescence is generally uniform and exhibits emission bands in the blue (470 nm with a shoulder at 522 nm) and in the UV (340 nm) regions of the spectrum. The branching ratio for the intensity of these bands is sensitive to the excitation energy across the Si K-edge. XANES spectra collected by partial luminescence yield (PLY) suggest that both emission bands originate from the de-excitation of Si atoms in the quartz. The possible defect sites within the crystal structure that could account for the observed luminescence are investigated and discussed. Additional experiments are proposed to verify this assignment of the optical emission bands.  相似文献   

11.
Natural calcite from Kuerle, Xinjiang, China, shows orange-red fluorescence when exposed to short-wave ultraviolet (UV) light (Hg 253.7 nm). Photoluminescence (PL) emission and excitation spectra of the calcite are observed at room temperature in detail. The PL emission spectrum under 208 nm excitation consists of three bands: two UV bands at 325 and 355 nm and an orange-red band at 620 nm. The three bands are ascribed to Pb2+, Ce3+ and Mn2+, respectively, as activators. The Pb2+ excitation band is observed at 243 nm, and the Ce3+ excitation band at 295 nm. The Pb2+ excitation band is also observed by monitoring the Ce3+ fluorescence, and the Pb2+ and Ce3+ excitation bands, in addition to six Mn2+ excitation bands, are also observed by monitoring the Mn2+ fluorescence. These indicate that four types of the energy transfer can occur in calcite through the following processes: (1) Pb2+ → Ce3+, (2) Pb2+ → Mn2+, (3) Ce3+ → Mn2+ and (4) Pb2+ → Ce3+ → Mn2+.  相似文献   

12.
Summary ?Feldspar specimens covering the whole Or–Ab–An ternary have been investigated by cathodoluminescence (CL), photoluminescence (PL), radioluminescence (RL) and radiophosphorescence (RP) spectrometry. A red luminescence emission, which is commonly explained by Fe3+ lattice defects, is a characteristic feature of all the spectra. Different shifts of the peak-wavelength between ∼680–750 nm (1.82–1.65 eV) were observed with varying feldspar composition. Despite the dependence of the peak position on the Ca/Na ratio, initially described for CL in the 1970s, there is also a shift induced by changing NaK composition. The observed effects can be explained by known relations that the peak position of the red luminescence emission in feldspars can be affected both by the structural state of the feldspar and the site occupancy of the trivalent iron. In the case of alkali feldspars another factor may influence the peak-shift. The incorporation of the larger potassium ion causes non-linear variations of the cell dimensions and therefore Fe–O bond distance. The behaviour of the red peak-shift dependent on the feldspar composition is not equal for all types of luminescence investigated. This is most likely caused by the different luminescence excitation mechanism. Received December 3, 2001; revised version accepted March 25, 2002  相似文献   

13.
Plates made of diamonds from the Sao Luiz province (Brazil) were investigated by confocal scanning luminescence microscopy. The samples have many macroinhomogeneities (cracks and inclusions), but there is a quasi-uniform distribution of luminescence centers in the bulk. At all investigated points of the crystals, the same group of centers was observed: N3, H4, 575, and a red band with a maximum at 690-700 nm. The visible nonuniformities in the distribution of luminescence over the area of the plates are determined by relatively small fluctuations in the ratio of the intensities of individual bands in the spectra. Nitrogen centers of different degrees of aggregation (H4, N3, and 575 nm, with four, three, and one nitrogen atom, respectively) coexist in these crystals. In the same zones of the samples, the distribution of blue luminescence (N3 centers) is diffuse (uniform), but the distribution of yellow-green luminescence is characterized by layering on (111). This might be a consequence of the tangential growth of octahedron faces or a result of plastic deformation of the crystals and dislocations along (111).  相似文献   

14.
Calcite was synthesized by four methods, and the luminescence decay-time was measured for nine samples before and after heating hydrothermally in the temperature range 200–400°C. Decay-time data were collected between room temperature and approximately 15 K. The decay time at room temperature is approximately 50 ms, with little difference between a given calcite before and after hydrothermal treatment. The decay time at 15 K is always greater than at room temperature as the effect of thermal quenching diminishes. Differences in decay time before and after heating are more apparent at low temperature owing to this reduction in thermal quenching. The decay time decreased significantly in two samples, and an increase in decay time was observed in the remaining seven samples following heating. Among the latter group, the change in decay time was insignificant in three samples. The results are compared with previous data in which it was shown that the effect of heating is to increase the intensity of luminescence.  相似文献   

15.
The orientation dependence of the luminescence of a well-characterized plagioclase crystal at room temperature and 40 K is reported. A beam of H + ions was used to provide the excitation. Ion beam luminescence provides emissions effectively from the bulk of the material, and therefore minimizes the contribution to the luminescence from atypical regions. The intensity of the luminescence is strongly orientation-dependent. The intensity and photon energy, particularly of the red/infrared and yellow emission bands, vary significantly. We interpreted this as resulting from Fe 3+ and Mn 2+ activator ions, respectively, on crystallographic sites with low point symmetry. An emission at 860 nm was also significantly orientation-dependent. The blue luminescence showed the least variability. At room temperature, a 350 nm near-UV emission was noted, whereas at 40 K, emissions were at 240, 260, 300 and 340 nm. UV emissions may result from Na + diffusion along interfaces within the plagioclase, notably albite-law (010) twins. This variability has significant consequences for the use of single-crystal quantitative luminescence techniques. We have also studied the dependence of the peak intensities and profiles during prolonged ion beam bombardment with heavier (He +) ions. Broadening of the red-infrared emission is interpreted as reflecting growing amorphization of the sample.  相似文献   

16.
从光致发光光谱角度探讨了海南蓬莱蓝宝石的呈色机理.结果发现:与蓝宝石吸收光谱的500～700 nm吸收宽带相比,在500～720 nm发光波段内存在566.8 nm锐峰、600 nm左右肩峰和Cr~(3+)的694.2 nm特征峰.600 nm肩峰与其吸收峰镜像对称,566.8 nm处锐峰的产生原因复杂.600 nm肩峰可能与Fe~(2+)-Fe~(2+)离子对的电子跃迁有关;566.8 nm锐峰因532 nm激光激发Fe~(2+)-Ti~(4+)或Fe~(2+)-Fe~(3+)间的电荷迁移带,通过晶格造成Si~(4+)、Mg~(2+)等微量杂质离子敏化而产生.光致发光谱中呈现更多谱峰,能呈现离子跃迁时不同离子间发生的相互作用,为500～700 nm吸收宽带由不同致色机制的叠加给出了直接证明,是一种能全面地研究宝石矿物中致色元素能级结构的有效方法.  相似文献   

17.
Summary The temperature dependence of photoluminescence emission of a natural fluorite has been studied in the wavelength region of 380–500 nm and in the temperature range of 17.5–300 K. The emission spectra of the sample show a broad emission band between 380 and 500 nm for temperatures above 100 K. At 100 K and below, vibronic lines appear on the emission band at approximately 413.3, 418.1, 419.3, 420.2, 423.9 and 427.1 nm. This broad emission band and the vibronic lines in fluorite are usually associated with phonon-coupled electronic transitions from 4f65d to 4f7 in the Eu2+ ion. Temperature dependences of the peak energy, intensity and full-width at half-maximum of the broad emission band are discussed, and the behaviour explained in terms of a configurational coordinate model. The excited state vibrational energy was obtained to be 0.023 ± 0.001 eV and this is lower than the LO phonon energy of 0.062 eV in pure fluorite. The activation energy of thermal quenching of the photoluminescence intensity was found to be 0.022 ± 0.002 eV.  相似文献   

18.
The present work aim to study the effect of burial on the photoluminescnece (PL) spectra of white, crystalline marble surfaces and the physicochemical processes that take place at the marble—soil interface. The PL was studied by an argon ion laser beam, focused through a microscope objective onto the sample, offering a spatial resolution of 3 μm. Long-buried (time scale of 1,000 years) surfaces show a red (at 610 nm) emission due to Mn2+, which is also shown on fresh marble spectra and an additional broadband blue-green (380–530 nm) one. Electron paramagnetic resonance (EPR) spectroscopy and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) indicate that the latter emission originates from humate complexes. The complexes are most probably Ca-humates, the humic substances found in the soil and the divalent calcium cations released by the dissolution of marble calcite. Finally, the examination of recently (time scale of 50 years) buried surfaces shows that the blue-green emission and consequently the presence of humates in marble patinas are not affected by the soil organic matter content. Soil acidity however, is a critical factor, with a total absence of the blue-green emission at pH values lower than 6.  相似文献   

19.
采用显微观察、红外光谱、可见吸收光谱和低温光致发光谱等分析方法,对9颗俄罗斯高温高压处理钻石样品进行了研究。结果表明,该类钻石样品的内部多见石墨化现象,尤以彩色钻石样品更明显;金黄色、紫红色、黄绿色样品为ⅠaAB型,浅黄色样品为ⅠaB型,近无色样品为Ⅱa型;样品的可见吸收光谱因颜色不同而差异显著,其中金黄色样品可见475 nm处的吸收宽带,紫红色样品可见638,614,595 nm处的吸收峰,黄绿色和浅黄色样品可见415,475,503 nm处的吸收峰,近无色样品则为较光滑的平直曲线。此外,该类样品在低温光致发光谱中可见575 nm与637 nm处强发光峰。这些特征为探讨该类钻石的晶格缺陷与呈色机理提供了一定的科学依据。  相似文献   

20.
The ultrafast transient photoluminescence of impact silica-rich glasses and nanostructured opals is investigated at the (sub)nanosecond time scale. Spectral and temporal data were acquired with a high-resolution streak camera under high-density energy laser excitation at 4.17 eV (297 nm). All samples reveal blue photoluminescence relaxing in less than 50 ns. Relaxation decays and luminescence energy vary strongly from opals to impact glasses. Opals are found to relax in less than 16 ns with a maximum emission at 2.6–2.8 eV (443–477 nm) while the high-silica glasses exhibit a much longer luminescence in the 50-ns time window, which is spectrally blueshifted towards 3.0–3.5 eV (354–413 nm). Results are interpreted in terms of the presence of nonbridging oxygen atoms, network modifiers, and nanostructures which produce emission from self-trapped excitons and from excitons recombining at surface defects. The short-lived emissions of opals are characteristic of intrinsic surface photoluminescence quenched after about 10 ns via nonradiative decay channels with an annihilation component, and involve recombination luminescence of self-trapped excitons.  相似文献   

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