The use of t he ellipsometer for t he m eas urpment of the thickn ess a nd refra ctive index of very thin film s is reviewed . The P o in care sphere representatio n of t he state of p ola rizat io n of light is de \'elop ed a nd used to desc ribe t he reflection process. D etails of the operation of t he ellipso meter a rc examined criticall y. A co mpu tatio nal mC'thod is prese nted by whi ch the thickness of a film of known refractive ind ex on a re fl ecting s ubstrate of known optical co nstants ma y be calculated direc t ly from the ellipsometer r ea din g~. A met hod for co mpu tin g both the refractivc index a nd thickn ess of an unkn own film is also d e veloped. These meth ods have been applied to the det erminat ion of th e th ick ness of a n adso rbed water layer on chromium ferrotyp e p la t es and on gold s urfaces. In th c former case the t hi ck ness , ras 23 to 27 A, a nd in the lat,tc r was 3 to 5 A. Th e meas urement of the th ickness and refractive index of barium fiu ori de film s c\'aporated 0 11 ch romiu m fC'ITotyp e s urfaces is used a s a n illust ration of t h e simu ltaneous d eterlllin a tion of these t wo qu a ntiti es .

T he behavior of an infi nitely long flexib le fil a men t after transverse impact is treated theoret.icall y. The fil a ment is ass u med to have a tension-strain curve that is always co ncave dow nward, and to have no short-ti me creep or stress-rei fixation effects. Under most cond itions the impact in itiates a varia bl e strain t hat prop agates down the fil a ment between an "elasLic wave" fro nt a nd a " plastic wave" front. A tra nsverse wave, shaped li ke an inverLed V, then travels in t he co nstan t-strain region behin d the plastic-wave front. Under specia l condi tio ns t he transverse-wave front may propagate faster than the plastic-wave front, b ut the sh ape of t he tra nsverse wave r ema ins t he sam e. T he theory for both cases is worked out in d etail , an d some ill ustrative examples arc given.

A general Fortran program is given that performs the calculations required to analyze ellipsometer measurements. This program replaces the program given in NBS Technical Note 242, entitled "A Fortran Program for Analysis of Ellipsometer Measurements and Calculation of Reflection Coefficients From Thin Films." The main changes from the previous program are: 1) the new program is in Fortran IV and V rather than Fortran II; 2) the relative transmission of the wave plate is considered in analyzing ellipsometer readings; 3) an improved method is used for calculating the refractive index of a film; 4) the form of the input data is improved; 5) a method for calculating and correcting for tilt of the reflecting surface is given; 6) an improved method of calculating confidence limits for the calculated values of thickness and refractive index of a film is used; and 7) a method for calculating the optical constants of an adsorbing film of given thickness is included.

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A detailed treatment of the conformations of a one-dimensional polymer molecule adsorbed to a surface is given. The average number of contacts of the chain with the surface, the end-to-end length, and the distribution of segments ρ(z) with respect to distance z from the surface are computed as functions of the chain length (N) of the polymer and the attractive energy of the surface. Both theoretical and Monte Carlo calculations are used. A transition is found at an attractive energy of kT ln 2. For attractive energies less than this value, the average number of contacts of the chain with the surface approaches a finite value as N approaches infinity, while the end-to-end length vaires as N½. However, above the transition the number of contacts is proportional to N and the end-to-end length is independent of N. The distribution of segments ρ(z) also shows a marked change as we go through the transition. The one-dimensional model is shown to correspond to the projection of a three-dimensional model on the direction normal to the surface. Therefore, these results are believed to represent the distribution normal to the surface for real systems.