稀土掺杂固体发光材料的光谱分析

Spectral Analyses of Rare-Earth Ions in Solid Luminescent Materials

光谱分析是评价稀土发光材料光谱性质的主要依据,Judd-Ofelt(J-O)理论是光谱分析的基础。详述了采用J-O模型拟合三个强度参量和估算一些重要辐射参量的操作细节,讨论了相关公式的合理应用,总结了计算中误差的主要来源,并推荐了一种通过低温实验获得较可靠光谱参量的途径。建议采用透射光谱数据计算实验跃迁振子强度,吸收系数和吸收截面的计算应该扣除光反射、散射和基质本身吸收的影响,平均波数和平均波长的取值须考虑线形因子。并建议通过发射光谱的实测线形计算各波长的发射截面。由于J-O模型涉及许多近似和假设,计算结果误差较大,可能导致结果不可靠。通过分析指出,采用低温下测得的能级寿命和荧光分支比进行相关参量的估算可获得较可靠、较有意义的结果。

Spectral analyses are the basis of estimating spectroscopic properties of rare-earth ions doped materials and Judd-Ofelt （J-O） theory is considered the foundation of spectral analyses. The process calculating three intensity parameters according to J-O model and some important radiative parameters are detailed; the reasonable applications of related formulas are discussed; the originations of errors in calculations are summarized, and a different approach is recommended to obtain more reliable radiative parameters. Experimental oscillator strengths are suggested to be calculated by transmission spectra. The light reflection, scattering and the inherent absorption of matrix should be subtracted in absorption coefficient and cross-section calculations. The line shape factor must be taken into account for determining the average wavenumber and wavelength. The line shape of measured emission spectrum is proposed to be considered for calculating emission cross-sections at different wavelength. However, the errors are usually relatively high, even leading to unreliable results, because many approximations and assumptions were involved in J- O model. It is put forward that if measured radiative lifetimes and branching ratios at low temperature are used to calculate parameters, obtained results will be more reliable and meaningful.