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X‐ray photochemistry: ω‐Chloro olefin sulfones
Author(s) -
Kaplan Michael
Publication year - 1983
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.760231708
Subject(s) - chlorine , absorption (acoustics) , polymer , olefin fiber , materials science , absorption edge , intramolecular force , photochemistry , irradiation , absorbed dose , side chain , organic chemistry , chemistry , band gap , optoelectronics , composite material , physics , nuclear physics , metallurgy
Abstract To be efficacious as an x‐ray resist, a material must efficiently undergo a desirable chemical change upon being irradiated with x‐rays. The probability of such a change taking place is given by the product of the fractional x‐ray absorption and the “inherent sensitivity,” which we define as the yield per unit energy absorbed. Increasing the absorption of the polymer, as, for example, by chlorinating an olefin sulfone thereby increasing the absorption at wavelengths just below the chlorine absorption edge will result in improved usefulness if, and only if, this increased energy absorbed can be used by the polymer to enhance the desired chemical reaction. The “usefulness” of chlorinating is thus dependent on the efficiency of intramolecular energy transfer. We have studied the efficiency of this transfer by monitoring the loss of SO 2 from the main‐chain backbone as a function of absorbed x‐ray energy, using x‐ray wavelengths both abov and below the chlorine absorption edge. The polymers studied were 1‐olefin sulfones, with and without the chlorine atom in the ω‐position. Through the use of this series of polymers it was hoped to observe an effect due to the changing separation of the chlorine atom from the backbone. The experiments indicate that (a) the inherent sensitivity is independent of irradiating wavelength, for both the chlorine‐containing and the non‐chlorine‐containing polymers; (b) the hexene polymers are considerably more sensitive than the lower members of the series (which exhibit a sensitivity which is approximately independent of the side chain length); and (c) the chlorine‐containing polymers are less sensitive than the non‐chlorine‐containing species. At this time the explanation for these observations is speculative.