Hurst Wilbur S, Choquette Steven J, Etz Edgar S
Chemical Science and Technology Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA.
Appl Spectrosc. 2007 Jul;61(7):694-700. doi: 10.1366/000370207781393235.
The relative intensity correction of Raman spectra requires the measurement of a source of known relative irradiance. Raman spectrometers that employ two-dimensional charge-coupled device (CCD) array detectors may be operated in two distinct modes. One mode directly measures the counts in each CCD pixel, but more commonly for the collection of spectra, the counts in the CCD row pixels are summed for a given column. If distortions in the corrected spectral shapes are to be avoided, operation in the mode where rows are summed places restrictions on the spatial intensity profile of the source of known irradiance that is used for the relative intensity correction procedure and, in some cases, also on the spatial intensity profile of the measured Raman light. Numerical expressions are given from which these restrictions can be derived. Magnitudes of distortions that can arise when intensity-correcting spectra obtained with CCD data where rows in a column are summed are estimated by modeling different cases. Data are given showing the inherent pixel quantum efficiency variation that exists in CCDs. Spectra are given showing the effects of a local area of significant change in pixel quantum efficiency that was found to be present on one CCD detector.
拉曼光谱的相对强度校正需要测量已知相对辐照度的光源。采用二维电荷耦合器件（CCD）阵列探测器的拉曼光谱仪可以在两种不同模式下运行。一种模式直接测量每个CCD像素中的计数，但更常见的光谱采集模式是，对于给定的列，将CCD行像素中的计数进行求和。如果要避免校正后的光谱形状出现失真，在行求和模式下运行会对用于相对强度校正过程的已知辐照度光源的空间强度分布以及在某些情况下对所测量拉曼光的空间强度分布施加限制。文中给出了可从中推导出这些限制的数值表达式。通过对不同情况进行建模，估计了在对列中行求和的CCD数据进行强度校正光谱时可能出现的失真幅度。给出了显示CCD中存在的固有像素量子效率变化的数据。给出了光谱，展示了在一个CCD探测器上发现的像素量子效率显著变化的局部区域的影响。
