Emerald is a green(Cr-bearing)variety of beryl.It has also been one of the highest value and highly demanded gemstones in the world.For this reason,the methods for synthesis emerald(i.e.,hydrothermal,flux grown)have b...Emerald is a green(Cr-bearing)variety of beryl.It has also been one of the highest value and highly demanded gemstones in the world.For this reason,the methods for synthesis emerald(i.e.,hydrothermal,flux grown)have been constantly developed.In many cases,it is hard to distinguish the natural emerald from the synthetic one using the basic instruments.Therefore,with the advantage of non-destructive technique,the infrared spectroscopy has been efficiently applied for the task.In this study,to find the potential technique in FTIR spectroscopy for classifying between natural and synthetic emerald(hydrothermal and flux-grown),the observed spectra from the Attenuated Total Reflectance Radiation(ATR),Diffuse Reflectance(DRIFT),transflectance,and specular reflection techniques were compared.The result showed that the spectra obtained from the transflectance and the DRIFT techniques were similar with equal spectral qualities.Unlike the diffuse reflectance spectra,the transflectance spectra were not affected by the sample orientations.The spectral features associated with water molecule in the crystal structure were clearly observed in both the DRIFT and transflectance spectra.Although the spectral features associated with weak absorption bands of water were not observed in both the DRIFT and transflectance spectra,the position of strong absorption band at 3 800-3 500 cm^(-1) and 1 635 cm^(-1) could be detected in the ATR spectra.In addition,the lack of absorption of water between 4 000 and 3 400 cm^(-1) in flux-grown emerald samples is the clue to separate it from the natural and hydrothermal one.In the meantime,the absence of the strong absorption peaks between 2 300 and 1 400 cm^(-1) in hydrothermal emerald can differentiate it from the natural one.展开更多
To find out the colouring mechanism and the form of water molecule of ouilin hydrothermally-grown sguthetic emerald, the test of electronic probe and the test of the spectrum etc are adopted in the research. The resul...To find out the colouring mechanism and the form of water molecule of ouilin hydrothermally-grown sguthetic emerald, the test of electronic probe and the test of the spectrum etc are adopted in the research. The result shows that Guilin hydrothermally-grown synthetic emerald is characterhed by low content of alkali and Fe but some are out of Cl; both Ⅰ -troe and,Ⅱ -type water exist. Its colour should be attributed to the separation of F-spectrum term and spectrum term of electrons jumping between the different emerge levels. Moreover, nail-like inclusions of three facies and microwave patterns often exist, which can be regarded as identified f6atures of this kind of emeralds, and FTIR can be applied to identibog all kinds of emeralds.展开更多
文摘Emerald is a green(Cr-bearing)variety of beryl.It has also been one of the highest value and highly demanded gemstones in the world.For this reason,the methods for synthesis emerald(i.e.,hydrothermal,flux grown)have been constantly developed.In many cases,it is hard to distinguish the natural emerald from the synthetic one using the basic instruments.Therefore,with the advantage of non-destructive technique,the infrared spectroscopy has been efficiently applied for the task.In this study,to find the potential technique in FTIR spectroscopy for classifying between natural and synthetic emerald(hydrothermal and flux-grown),the observed spectra from the Attenuated Total Reflectance Radiation(ATR),Diffuse Reflectance(DRIFT),transflectance,and specular reflection techniques were compared.The result showed that the spectra obtained from the transflectance and the DRIFT techniques were similar with equal spectral qualities.Unlike the diffuse reflectance spectra,the transflectance spectra were not affected by the sample orientations.The spectral features associated with water molecule in the crystal structure were clearly observed in both the DRIFT and transflectance spectra.Although the spectral features associated with weak absorption bands of water were not observed in both the DRIFT and transflectance spectra,the position of strong absorption band at 3 800-3 500 cm^(-1) and 1 635 cm^(-1) could be detected in the ATR spectra.In addition,the lack of absorption of water between 4 000 and 3 400 cm^(-1) in flux-grown emerald samples is the clue to separate it from the natural and hydrothermal one.In the meantime,the absence of the strong absorption peaks between 2 300 and 1 400 cm^(-1) in hydrothermal emerald can differentiate it from the natural one.
文摘To find out the colouring mechanism and the form of water molecule of ouilin hydrothermally-grown sguthetic emerald, the test of electronic probe and the test of the spectrum etc are adopted in the research. The result shows that Guilin hydrothermally-grown synthetic emerald is characterhed by low content of alkali and Fe but some are out of Cl; both Ⅰ -troe and,Ⅱ -type water exist. Its colour should be attributed to the separation of F-spectrum term and spectrum term of electrons jumping between the different emerge levels. Moreover, nail-like inclusions of three facies and microwave patterns often exist, which can be regarded as identified f6atures of this kind of emeralds, and FTIR can be applied to identibog all kinds of emeralds.
