With the recent development[1] of planar array infrared (PA-IR) spectroscopy, a re-examination of the usefulness of IR spectroscopy in terms of studying dynamic processes is warranted. This talk will describe an ultrafast, portable PA-IR instrument and its application to the dynamics of polymer organization during assembly of a Langmuir film at the air-water interface.

PA-IR spectroscopy offers a number of advantages over conventional Fourier transform infrared (FT-IR) methods and traditional dispersive infrared instruments, such as a multi-channel advantage, a short integration time, pixel binning options, scaleable optics, and no moving parts. Obtaining a spectrum in the range of 1800-1000 cm-1 of films on the water subphase still remains difficult due to the poor IR reflectivity of water, the extremely low concentration of the ultra thin film and the interference of water bands. In this talk, a new planar array infrared reflection spectrograph (PA-IRRS), which has several advantages over conventional approaches, will be discussed. By splitting the incident infrared beam into two sections on a plane mirror or a water trough, instead of at the front of the globar source, the performance of this instrument is shown to be comparable to that of the dual-beam instrument, although this instrumental setup is the same as that of the single-beam instrument. This PA-IRRS system has significant potential for investigating the time-resolved dynamics of a broad range of Langmuir films, such as cellular membranes or biopolymers, on the water subphase.

[1] D. Elmore, M.W. Tsao, D.B. Chase, J.F. Rabolt, Applied Spectroscopy 56 (2002) 145.