A fundamental task of chemically amplified photoresists is to record the incident radiation by generating catalyst concentration gradients within the film. In many resists, the catalyst is a strong Bronsted acid which yields a latent image of pH within the exposed film. A number of mechanistic questions remain about acid generator efficiency and its mobility once generated and heated. We have developed a technique in which a pH-dependent fluorophore is incorporated into the resist (an undyed version of SAL 605 from the Shipley Company and similar formulations). The localized acid concentrations generated by exposure to x-rays are analyzed and imaged using fluorescence spectroscopy and microscopy. Initial experiments, the spectroscopic apparatus, and initial far-field imaging are reported elsewhere [S. J. Bukofsky, G. D. Feke, Q. Wu, R. D. Grober, P. M. Dentinger, and J. W. Taylor, Appl. Phys. Lett. 73, 3 (1998)]. In this article, several fluorophores are evaluated, and various criteria for successful imaging within the photoresist matrix are established. These criteria include pK(a) of the fluorophore, photostability, and functional groups that-affect the performance of the acid within the film. The technique is used to show the relative efficiency of two photoacid generators in otherwise identical matrices, and the method has the potential for rapid photogenerated acid yield determination among a variety of photoacid generators. This technique can be used in thin imaging films and, due to the low level of fluorophore required (0.01-0.1 wt. %), for photoacid yield determination in optical photoresists without significantly altering the absorbance characteristics of the film. Initial near-field scanning optical microscopy images are shown and the potential of the technique for several lithographic applications, including measurement of the actual spread of the acid distribution during postexposure bake, is discussed.