Several misprints have been found in this article.
1. The authors' names are Albert Sanfeld and Annie Steinchen.
2.Eq. (15) should be written:
| (15) |
3.Eq. (18) should be written:
| (18) |
4.Table 3 should be as follows:
| ℓ (μm) | |
| 1 | 1 |
| 0.1 | 1.1 |
| 0.01 | 2.5 |
| 0.005 | 6.4 |
