اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدIonized Nitrogen Mono-hydride Bands are Identified in the Pre-solar and Carbonado Diamond Spectra
35
0
0.0
(
0
)
تأليف
Jozsef Garai
اسأل ChatGPT حول البحث
ﻻ يوجد ملخص باللغة العربية
None of the well established Nitrogen related IR absorption bands, common in synthetic and terrestrial diamonds, have been identified in the pre-solar diamond spectra. In the carbonado diamond spectra only the single nitrogen impurity (C centre) is identified and the assignments of the rest of the nitrogen-related bands are still debated. It is speculated that the unidentified bands in the Nitrogen absorption region are not induced by Nitrogen but rather by Nitrogen-hydrides because in the interstellar environment Nitrogen reacts with Hydrogen and forms NH+; NH; NH2; NH3. Among these Hydrides the electronic configuration of NH+ is the closest to Carbon. Thus this ionized Nitrogen-mono-hydride is the best candidate to substitute Carbon in the diamond structure. The bands of the substitutional NH+ defect are deduced by red shifting the irradiation induced N+ bands due to the mass of the additional Hydrogen. The six bands of the NH+ defects are identified in both the pre-solar and the carbonado diamond spectra. The new assignments identify all of the nitrogen-related bands in the spectra, indicating that pre-solar and carbonado diamonds contain only single nitrogen impurities.
قيم البحث
اقرأ أيضاً
The variation with time from 1956-2002 of the globally averaged rate of ionization produced by cosmic rays in the atmosphere is deduced and shown to have a cyclic component of period roughly twice the 11 year solar cycle period. Long term variations
in the global average surface temperature as a function of time since 1956 are found to have a similar cyclic component. The cyclic variations are also observed in the solar irradiance and in the mean daily sun spot number. The cyclic variation in the cosmic ray rate is observed to be delayed by 2-4 years relative to the temperature, the solar irradiance and daily sun spot variations suggesting that the origin of the correlation is more likely to be direct solar activity than cosmic rays. Assuming that the correlation is caused by such solar activity, we deduce that the maximum recent increase in the mean surface temperature of the Earth which can be ascribed to this activity is $lesssim14%$ of the observed global warming.
We report a study of the magnetic field dependence of photoluminescence of NV$^-$ centers (negatively charged nitrogen-vacancy centers) in diamond single crystals. In such a magnetic field dependence characteristic sharp features are observed, which
are coming from Level Anti-Crossings (LACs) in a coupled electron-nuclear spin system. For sensitive detection of such LAC-lines we use lock-in detection to measure the photoluminescence intensity. This experimental technique allows us to obtain new LAC lines. Additionally, a remarkably strong dependence of the LAC-lines on the modulation frequency is found. Specifically, upon decrease of the modulation frequency from 12 kHz to 17 Hz the amplitude of the LAC-lines increases by approximately two orders of magnitude. To take a quantitative account for such effects, we present a theoretical model, which describes the spin dynamics in a coupled electron-nuclear spin system under the action of an oscillating external magnetic field. Good agreement between experiments and theory allows us to conclude that the observed effects are originating from coherent spin polarization exchange in a coupled spin system comprising the spin-polarized NV$^-$ center. Our results are of great practical importance allowing one to optimize the experimental conditions for probing LAC-derived lines in diamond crystals comprising NV$^-$ centers and for indirect detection and identification of other paramagnetic defect centers.
The dependence of the luminescence of diamonds with negatively charged nitrogen-vacancy centers (NV-) vs. applied magnetic field (magnetic spectrum) was studied. A narrow line in zero magnetic field was discovered. The properties of this line are con
siderably different from those of other narrow magnetic spectrum lines. Its magnitude is weakly dependent of the orientation of the single-crystal sample to the external magnetic field. This line is also observed in a powdered sample. The shape of the line changes greatly when excitation light polarization is varied. The magnitude of the line has a non-linear relation to excitation light intensity. For low intensities this dependence is close to a square law. To explain the mechanism giving rise to this line in the magnetic spectrum, we suggest a model based on the dipole-dipole interaction between different NV- centers.
We report measurements of the optical properties of the 1042 nm transition of negatively-charged Nitrogen-Vacancy (NV) centers in type 1b diamond. The results indicate that the upper level of this transition couples to the m_s=+/-1 sublevels of the {
^3}E excited state and is short-lived, with a lifetime <~ 1 ns. The lower level is shown to have a temperature-dependent lifetime of 462(10) ns at 4.4 K and 219(3) ns at 295 K. The light-polarization dependence of 1042 nm absorption confirms that the transition is between orbitals of A_1 and E character. The results shed new light on the NV level structure and optical pumping mechanism.
We report a study of the magnetic field dependence of the photo-luminescence of NV$^-$ centers (negatively charged nitrogen-vacancy centers) in diamond single crystals. In such a magnetic field dependence characteristic lines are observed, which are
coming from Level Anti-Crossings (LACs) in the coupled electron-nuclear spin system. For enhancing the sensitivity, we used lock-in detection to measure the photo-luminescence intensity and observed a remarkably strong dependence of the LAC-derived lines on the modulation frequency. Upon decreasing of the modulation frequency from 12 kHz to 17 Hz the amplitude of the lines increases by approximately two orders of magnitude. To take a quantitative account for such effects, we developed a theoretical model, which describes the spin dynamics in the coupled electron-nuclear spin system under the action of an oscillating external magnetic field. Good agreement between experiments and theory allows us to conclude that the observed effects are originating from coherent spin polarization exchange in the NV$^-$ center. Our results are of great practical importance allowing one to optimize the experimental conditions for probing LAC-derived lines in diamond defect centers.
سجل دخول لتتمكن من نشر تعليقات
التعليقات
جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
