The ability of a planar array infrared (PA-IR) spectrograph to obtain spatially resolved infrared spectra (infrared line images) of a monolayer film with reasonable signal-to-noise-ratios is demonstrated, and the first infrared line images of a monolayer film ever recorded are reported. In this context, octadecyltrichlorosilane (OTS) monolayer films self-assembled on glass substrates were investigated as a function of three different solvents (hexane, benzene, and toluene). It is shown that the PA-IR line images could be used to investigate surface coverage and conformational order as a function of spatial location. A frequency versus absorbance relationship was observed that can be interpreted as a well-defined correlation between conformational order and surface coverage. The plot of this relationship, which looks similar to a phase diagram containing a first-order phase transition, is in excellent agreement with that reported recently (Liu, Y.; Wolf, L. K.; Messmer, M. C. Langmuir 2001, 17, 4329) by su...