được thành lập bằng cách đo quang phổ rung động kết hợp với việc xác định các trang web hấp thụ CO crystallographycalculations LEED, và cũng bằng cách kiểm tra các mối tương quan cho CO ngoại quan trong các cụm cơ kim. Tương quan tương tự cũng có khả năng tồn tại cho có hai nguyên từ các phân tử khác liên kết các bề mặt, ví dụ như, | 7SSSSSS SSSSSA Figure 4 Specular spectra in HREELS of NO2 adsorbed in three different bonding 9 I 9 9 ML O Pt 111 been established by measuring the vibrational spectrum in conjunction with determining the adsorption site for co by LEED crystallography calculations and also by examining the correlations for co bonded in organometallic clusters. Similar correlations are likely to exist for other diatomic molecules bonded to surfaces . NO based on correlations observed in organometallic clusters but this has not been investigated sufficiently. Figure 5 shows the utility of HREELS in establishing the presence of both bridge-bonded and atop co chemisorbed on Pt l 11 and two SnPt alloy surfaces and also serves to emphasize that HREELS is very useful in studies of metal The V 2O peaks for co bonded in bridge sites appear at 1865 1790 and 1845 cm-1 on the Pt lll 2 X 2 and a 3 surfaces respectively. The vco peaks for co 452 VIBRATIONAL SPECTROSCOPIES. Chapters ENERGY LOSS cm 1 Figures HREELS of the saturation coverage of co on Pt 111 and the 2 X 2 and ựã X Ự3 R30 Sn Pt surface bonded in atop sites appear at 2105 2090 and 2085 cm-1 on the Pt l 11 2 X 2 and 73 surfaces respectively. Also lower frequency vpt-CO peaks accompany each of the Vqq peaks. As discussed previously the peak intensities are not necessarily proportional to the concentration of each type of co species and the exact V 2O frequency is determined by many factors. Other Applications Many other surfaces can be investigated by HREELS. As larger molecule and nonsingle-crystal examples we briefly describe the use of HREELS in studies of polymer surfaces. The usefulness of HREELS specifically in polymer surface science HREELS 453 0 2000 4000 600 1000 1400 1000 Wave Number cm-1 Figure 6 Vibrational spectra of polymere a Transmission infrared spectrum of polyethylene t l electron-induced loss spectrum of polyethylene cl transmission infrared spectrum of .
