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ll921木虫 (正式写手)
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shows the dependence of (αhν)1/2 on hν in the energy range from 3.2 eV to 3.8 eV (387~326 nm), where two distinct straight lines are seen for the as-grown shows the dependence of (αhν)1/2 on hν in the energy range from 3.2 eV to 3.8 eV (387~326 nm), where two distinct straight lines are seen for the as-grown xxx crystal. In this case, the absorption coefficient data has been fitted and extrapolated to (αhν)1/2=0, so the values of E1= Egi+Ep and E2= Egi−Ep have been obtained as E1=3.38 eV and E2=3.2 eV. So the indirect energy gap of Zn2TiO4 and the phonon energy can be determined as Egi= 1/2(E1+E2)= 3.29 eV and Ep= 1/2(E1−E2)= 0.09 eV (or 721 cm−1), respectively. Raman spectroscopy is a useful method to study the phonon vibration characteristics [8, 30]. Fig. 4 gives the polarized Raman spectra for the as-grown xxx crystal at room-temperature. It can be seen that the Raman modes of 257 (F2g), 308 (Eg), 348 (F2g) and 721 (Ag) cm-1 appear in the VV geometry, and the Raman modes of 257 (F2g), 308 (Eg), 348 (F2g) and 478 (F2g) cm-1 Raman modes appear in the VH configuration, which reflects obviously the Raman selection rules. Other two modes, located at 154 and 567 cm-1, do not belong to the Raman active modes of spinel xxx. The mode at 154 cm-1 was interpreted to be possibly caused by the laser-induced plasma effect. And the mode at 567 cm-1 was assigned to be likely caused by an order-disorder effect of x and x ions over the octahedral and tetrahedral sites [8, 11]. In the as-grown crystal, x and x ions are ordered orientally, so the mode 567 cm-1 shows an orientation dependence character. It can be also found that the intensity of the phonon mode at 721 cm-1 in the VV geometry is very strong and its energy (0.09 eV) is also the highest among all active phonons. More importantly, the phonon energy of the Raman mode at 721 cm-1 in the Raman spectra agrees perfectly with the phonon energy calculated from the absorption spectrum. Therefore, it is reasonable to believe that the indirect transitions of xxx are mainly due to the contribution of the 721 cm-1 phonon. crystal. In this case, the absorption coefficient data has been fitted and extrapolated to (αhν)1/2=0, so the values of E1= Egi+Ep and E2= Egi−Ep have been obtained as E1=3.38 eV and E2=3.2 eV. So the indirect energy gap of Zn2TiO4 and the phonon energy can be determined as Egi= 1/2(E1+E2)= 3.29 eV and Ep= 1/2(E1−E2)= 0.09 eV (or 721 cm−1), respectively. Raman spectroscopy is a useful method to study the phonon vibration characteristics [8, 30]. Fig. 4 gives the polarized Raman spectra for the as-grown xxx crystal at room-temperature. It can be seen that the Raman modes of 257 (F2g), 308 (Eg), 348 (F2g) and 721 (Ag) cm-1 appear in the VV geometry, and the Raman modes of 257 (F2g), 308 (Eg), 348 (F2g) and 478 (F2g) cm-1 Raman modes appear in the VH configuration, which reflects obviously the Raman selection rules. Other two modes, located at 154 and 567 cm-1, do not belong to the Raman active modes of spinel xxx. The mode at 154 cm-1 was interpreted to be possibly caused by the laser-induced plasma effect. And the mode at 567 cm-1 was assigned to be likely caused by an order-disorder effect of x and x ions over the octahedral and tetrahedral sites [8, 11]. In the as-grown crystal, x and x ions are ordered orientally, so the mode 567 cm-1 shows an orientation dependence character. It can be also found that the intensity of the phonon mode at 721 cm-1 in the VV geometry is very strong and its energy (0.09 eV) is also the highest among all active phonons. More importantly, the phonon energy of the Raman mode at 721 cm-1 in the Raman spectra agrees perfectly with the phonon energy calculated from the absorption spectrum. Therefore, it is reasonable to believe that the indirect transitions of xxx are mainly due to the contribution of the 721 cm-1 phonon. |
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2楼2012-09-21 15:25:25
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爱与雨下: 金币+2 2012-09-22 16:13:14
ll921: 金币+70, 翻译EPI+1, ★★★★★最佳答案 2012-09-23 09:46:57
爱与雨下: 金币+2 2012-09-22 16:13:14
ll921: 金币+70, 翻译EPI+1, ★★★★★最佳答案 2012-09-23 09:46:57
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Dependencies (αhν) hν from 3.2eV energy range of 3.8 EV (387 ~ 326 nm), wherein the two different lines as a native of 1/2 dependence (αhν) 1 / 2hν from 3.2 eV energy range to 3.8 eV (387 to 326 nm), where to see the two different linear growth XXX crystal. In this case, the absorption coefficient data fitting extrapolated to (αhν) 1/2 = 0 Therefore, the value E1 = EGI + EP and E2 = EGI-set has been E1 = 3.38 eV and E2 = 3.2 eV. Thus, indirect energy gap in the phonon energy of the luminescent properties, can be identified as EGI = 1/2 (E1 + E2) = 3.29 eV, and Ep = 1/2 (E1-E2) = 0.09 eV (or 721 cm -1), respectively. Raman spectroscopy is a useful method to study the the phonon vibration characteristics [9,30]. Figure. Figure 4 shows the polarized Raman spectra as the native XXX crystal at room temperature. As can be seen, its Raman mode 257 (F2G), 308 (for example), 348 (F2G) and the 721 (Ag) cm-1, appears in the geometry of the VV, and Raman mode 257 (F2G), 308 (for example), 348 (F2G) and 478 (F2G) cm-1 Raman modes appear in the VH configuration, which clearly reflects the Raman selection rules. The other two modes, at 154 and 567 cm-1, does not belong to the Raman active mode spinel XXX. Mode at 154 cm-1 is interpreted may be caused by the laser-induced plasma effect. In the 567 cm-1 at the mode assigned to may cause the order - disorder effects of X and X ions in octahedral and tetrahedral [10,11]. In the growth of crystals, x and x of the ion is ordered orientally, so the mode at 567 cm-1 showing the orientation dependent characters. It also can be found in the VV geometric strength phonon mode at 721 cm-1 is very powerful, highest phonon energy (0.09 eV) activities. More importantly, the phonon energy of 721 cm-1 at the Raman spectra of the Raman modes agree completely with the phonon energy is calculated from the absorption spectrum. Therefore, there is reason to believe that the indirect conversion xxx, mainly due to the contribution of the phonon at 721 cm-1. Crystals. In this case, the absorption coefficient data fitting extrapolated to (αhν) 1/2 = 0 Therefore, the value E1 = EGI + EP and E2 = EGI-set has been E1 = 3.38 eV and E2 = 3.2 eV. Thus, indirect energy gap in the phonon energy of the luminescent properties, can be identified as EGI = 1/2 (E1 + E2) = 3.29 eV, and Ep = 1/2 (E1-E2) = 0.09 eV (or 721 cm -1), respectively. Raman spectroscopy is a useful method to study the the phonon vibration characteristics [9,30]. Figure. Figure 4 shows the polarized Raman spectra as the native XXX crystal at room temperature. As can be seen, its Raman mode 257 (F2G), 308 (for example), 348 (F2G) and the 721 (Ag) cm-1, appears in the geometry of the VV, and Raman mode 257 (F2G), 308 (for example), 348 (F2G) and 478 (F2G) cm-1 Raman modes appear in the VH configuration, which clearly reflects the Raman selection rules. The other two modes, at 154 and 567 cm-1, does not belong to the Raman active mode spinel XXX. Mode at 154 cm-1 is interpreted may be caused by the laser-induced plasma effect. In the 567 cm-1 at the mode assigned to may cause the order - disorder effects of X and X ions in octahedral and tetrahedral [10,11]. In the growth of crystals, x and x of the ion is ordered orientally, so the mode at 567 cm-1 showing the orientation dependent characters. It also can be found in the VV geometric strength phonon mode at 721 cm-1 is very powerful, highest phonon energy (0.09 eV) activities. More importantly, the phonon energy of 721 cm-1 at the Raman spectra of the Raman modes agree completely with the phonon energy is calculated from the absorption spectrum. Therefore, there is reason to believe that the indirect conversion xxx, mainly due to the contribution of the phonon at 721 cm-1. |
3楼2012-09-22 09:08:42