A new method for evaluating surface passivation of silicon surfaces using a strongly adsorbing and fluorescing perylenediimide (PDI) dye is reported. Silanes containing differing reactive groups delivering a trimethylsilyl moiety were investigated for their ability to passivate glass surfaces, both from solution and in the vapor phase, as a function of temperature and concentration. Among the silanizing agents used in this study were 1,1,1,3,3,3-hexamethyldisilazane (HMDS), allyltrimethylsilane (TMS-A), chlorotrimethylsilane (TMS-CI), N-(trimethylsilyl)imidazole (TMS-Im), and N,N-dimethylaminotrimethylsilane (TMS-DMA). Surface coverage was determined using fluorescence intensity. The highest surface coverage films were obtained on glass treated with HMDS vapor at 280 degrees C or with solutions of TMS-Im or TMS-DMA at 105 degrees C. These studies provide important insight into the optimal methods for surface passivation.