68 JOURNAL OF COSMETIC SCIENCE three hole, sample cover masks, (Physical Electronics part # 612448) to hold the fibers co-planar and parallel. Double sided tape was placed on either side of the holes on the lower mask, the fibers (-20) cut to about 2" in length were placed and pressed onto the tape across the hole. The second mask was placed above the first, screws were run through both masks into the recessed sample mount (Physical Electronics part 606142) securing the fibers in place. The sample mount was placed within the spectrometer so that the hair fibers were oriented parallel to the source-analyzer plane. Instrument control, data collection and data analysis were performed with RBD Au­ gerscan V3 running on a Pentium PC. Quantization calculations were based on mea­ sured peak areas and empirical instrumental sensitivity factors. Curve fitting analysis employed a linear background and mixed Gaussian-Lorentzian peak shape. SEM Electron microscope images were collected with a Zeiss EVO-50 XVP instrument. This instrument is capable of operation from high vacuum to 700 Pa at the full range of electron beam voltages. Images for this work were collected with a secondary electron detector. Probe beam energy was 15 KV. A thin coating of Au was evaporated onto the surface of the fibers to minimize charge buildup. Magnifications of 1 Kx and 2.5 Kx are shown of the hair fibers at the various treatment stages of this study. RESULTS BLANK HAIR The natural hair surface is composed of C, 0, N, S, Si and Ca. A representative survey scan is shown in Figure 1. Note that in Figure 1, the 2s (-230 eV) and 2p (-185 eV) photoelectron transitions from S are observed as doublets. Each of these S photoelectron transitions is comprised of two unresolved peaks due to disulfide (-S-S-) links of the cystine amino acid and sulfonate (-S0 3 ). The formation of sulfonate groups is concen­ trated at the outer most surface where atmospheric oxygen, and UV illumination interact with the hair fiber (1,5). The observed nitrogen is present as a single chemical state, (399.8 eV) due to the amide, (peptide) links between amino-acids. Calcium and silicon were observed as naturally occurring constituents of the hair present in low levels ( 1.0 atom percent) consistent with previous work (4). Electron microscope images show the fibers to have ragged cuticle edges (Figure 2). The definition of the cuticle edges is obscured, particularly at lower magnification, presumably from deposits on the hair surface. BLEACHED HAIR Bleaching treatment gave widely varied results depending upon the time of treatment and the solution composition. Figure 3 is a survey scan of hair fibers after treatment with 3% hydrogen peroxide, at pH 9 for 45 minutes. There is a notable decrease in the about of surface carbon while the features due to 0, N, and S increased. Table II illustrates the surface compositional differences before and after bleaching.

N(E) Min: 23 Max: 55059 0(1s) 602 541,8 481,6 HAIR SURFACE CHEMISTRY C(1s) \ S(2s) S(2p) ��-�------�,� 69 421.4 361.2 301 240,8 180.6 120.4 60.2 -4.57764e-005 Binding Energy (eV) Figure 1. Survey scan of a blank hair sample. By tracking surface C content versus bleaching treatment solution and time, an indi­ cation of efficacy can be achieved. Figure 4 illustrates that the change in surface chem­ istry is most dramatic when the bleaching solution is at pH = 9 and surfactant is present. The hydrogen peroxide solution alone is relatively ineffective even over the 45 minute exposure period studied. Clearly the increased pH is an important factor and the small (0.25%) addition of surfactant has a measurable effect in addition. The chemical state information available from the high resolution XPS data clarifies the mechanism associated with this change in surface composition. Figure 5 is an overlay of the C(ls) high resolution spectra from the blank and bleached hair samples referred to in Table II. The blank hair spectrum is dominated by a single chemical state peak indicative of hydrocarbon (saturated, C-C/C-H bonding) at the outer most surface. After bleaching however, the surface has a much greater contribution from carbon associated with more electronegative elements (C-N/C-O bonding) which are present in the hair chemistry. This information leads to the conclusion that the bleaching removes a hy­ drocarbon overlayer revealing the hair structure itself. The removal of the hydrophobic hydrocarbon overlayer permits access of the water borne peroxide to the hair surface. Surfactancy imparted by the small addition of sodium lauryl sulfate allows more inti­ mate wetting of the surface and solvation of the hydrocarbon layer away from the hair fiber. The oxidative effect of hydrogen peroxide causes a measurable increase in the oxidized sulfur groups at the hair surface. Figure 6 shows the amount of oxidized sulfur groups at the surface resulting from the various bleaching treatments. The hydrogen peroxide solution alone had no effect, consistent with the very limited reduction in surface hydrocarbon overlayer content. The peroxide at elevated pH did oxidize the surface, however, after an induction time, where presumably the hydrocarbon overlayer