Table I.
XPS determined compositions of the NH2-SAMs on 24 nm AuNPs after undergoing a C11 NH2-thiol ligand-exchange with a C2 NH2-SAM for different lengths of time (30 min to 61 days). The data was normalized without the Ti signal as discussed in the text.
| at. % (std. dev.) | |||||
|---|---|---|---|---|---|
| Time of ligand-exchange | C1s | Au4f | N1s | O1s | S2p |
| 30 min | 23.6(3.8) | 64.6(3.1) | 5.3(0.8) | 2.2(0.5) | 4.4(0.4) |
| 3 h | 23.5(2.6) | 63.7(2.4) | 5.4(0.8) | 2.3(0.4) | 4.4(0.5) |
| 12 h | 25.9(3.7) | 61.9(3.6) | 5.4(0.8) | 2.3(0.3) | 4.5(0.4) |
| 24 h | 27.3(7.6) | 56.8(6.0) | 4.2(1.0) | 2.6(0.4) | 4.0(0.5) |
| 2 days | 36.2(5.1) | 52.5(4.8) | 4.5(0.4) | 2.8(0.3) | 4.0(0.3) |
| 4 days | 43.9(3.9) | 45.7(4.1) | 4.0(0.4) | 2.4(0.3) | 4.0(0.2) |
| 7 days | 47.5(4.2) | 42.3(4.0) | 4.2(0.5) | 2.1(0.3) | 3.9(0.4) |
| 14 days | 51.3(2.6) | 37.0(2.9) | 4.6(0.4) | 2.9(0.5) | 3.9(0.3) |
| 21 days | 51.6(1.2) | 36.4(0.9) | 4.7(0.4) | 3.5(0.6) | 3.6(0.4) |
| 31 days | 50.6(1.5) | 36.9(1.3) | 4.8(0.4) | 3.6(0.1) | 3.8(0.3) |
| 61 days | 52.3(1.5) | 35.5(1.1) | 4.8(0.3) | 3.3(0.5) | 3.9(0.3) |