Angle-dependent X-ray photoelectron spectroscopy (ADXPS) was used to investigate the role of sulfur in the binding of a 7250-base backbone-sulfur-modified deoxyribonucleic acid (DNA) nucleotide on a Au(111) film on mica. The quantitative depth profiles for carbon, nitrogen, oxygen, phosphorus, sulfur, and gold in the sample were calculated from the ADXPS intensity ratios using a novel algorithm. The results show an elevated concentration of sulfur and phosphorus between a multielement layer of the DNA molecule and the Au(111) surface, suggesting the DNA was bound to the Au(111) surface at the sulfur, as was our intention with this engineered polynucleotide. DNA surface coverage measurements made by atomic force microscopy (AFM) are compared to those made by the spatially averaged technique of XPS. The apparent coverage of DNA measured by AFM was several orders of magnitude less than that measured by XPS, suggesting that a large amount of DNA was swept out of the image area. The images presented are some of the first of DNA bound to a Au(111) surface as a direct result of the chemical modification of the DNA.