Table 6.
XPS determined composition for the methyl and carboxyl SAM. The C, O, N, and S atomic percents were renormalized to 100 atomic % to show the composition of theSAM overlayer. The Au atomic % before renormalization shows the attenuation of the gold signal by the SAM overlayer. The expected theoretical compositions for the SAMs are shown in italics.
| C (atomic %)* | O (atomic %)* | N (atomic %)* | S (atomic %)* | Au raw signal (atomic %) | |
|---|---|---|---|---|---|
| Methyl SAM | 96.5 ± 0.4 92.3 |
n.d.** 0.0 |
n.d. 0.0 |
3.5 ± 0.4 7.7 |
47.9 ± 1.7 |
| Carboxyl SAM | 81.7 ± 0.9 78.6 |
15.5 ± 1.0 14.3 |
n.d. 0.0 |
2.8± 0.1 7.1 |
40.5 ± 0.9 |
| Methyl SAM soaked in PBS buffer | 94.6 ± 0.7 92.3 |
2.3 ± 0.4 0.0 |
n.d. 0.0 |
3.1 ± 0.3 7.7 |
50.3 ± 1.4 |
*
Renormalized to 100% without the Au signal.
**
n.d. = not detected