Surface moiety | C (%) | S (%) | N (%) | O (%) | Si (%) | Contact angle (°) |
---|
Fused glass** | 25.0 (2.0) | * | <1.0 | 49.0 (2.0) | 22.0 (1.0) | 23 (4) |
Quartz (100) | 15.0 (2.0) | <1.0 | <2.0 | 53 (1.0) | 30.0 (3.0) | 13 (3) |
- An asterisk (*) indicates negligible value for atomic composition data. (Mean ± 95 % confidence interval, N = 3.)
- The presence of extra carbon composition is believed to be originating from surface contamination due to the exposure of samples to air after cleaning. These are the typical adventitious and unavoidable hydrocarbon impurities that adsorb spontaneously from ambient air onto the glass and quartz surface. However, since the surface carbon content also correlates strongly with the static water contact angle [38], our static water contact angle measurements show 23° for fused glass and 13° for quartz, which is quite comparable with expected values for clean silica substrates reported by many other groups [39–42], thus providing a good indicator that our standard cleaning protocol was effective
- ** Fused glass slide also contains Zn (<1 %) and Al (<1 %)