Structural characterization and comparison of iridium, platinum and gold/palladium ultra-thin film coatings for STM of biomolecules

Conference · Thu Oct 30 04:00:00 EST 1997

OSTI ID:463601

Sebring, R; Arendt, P; Imai, B; Bradbury, E M; Gatewood, J ^[1]; Panitz, J ^[2]; Yau, P ^[3]

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1. Los Alamos National Lab., NM (United States)
2. Univ. of New Mexico, Albuquerque, NM (United States). Dept. of Physics and Astronomy
3. Univ. of California, Davis, CA (United States)

Scanning tunneling microscopy (STM) is capable of atomic resolution and is ideally suited for imaging surfaces with uniform work function. A biological sample on a conducting substrate in air does not meet this criteria and requires a conductive coating for stable and reproducible STM imaging. In this paper, the authors describe the STM and transmission electron microscopy (TEM) characterization of ultra-thin ion-beam sputtered films of iridium and cathode sputtered gold/palladium and platinum films on highly ordered pyrolytic graphite (HOPG) which were developed for use as biomolecule coatings. The goals were the development of metal coatings sufficiently thin and fine grained that 15--20 {angstrom} features of biological molecules could be resolved using STM, and the development of a substrate/coating system which would allow complementary TEM information to be obtained for films and biological molecules. The authors demonstrate in this paper that ion-beam sputtered iridium on highly ordered pyrolytic graphite (HOPG) has met both these goals. The ion-beam sputtered iridium produced a very fine grained (< 10 {angstrom}) continuous film at 5--6 {angstrom} thickness suitable for stable air STM imaging. In comparison, cathode sputtered platinum produced 16 {angstrom} grains with the thinnest continuous film at 15 {angstrom} thickness, and the sputtered gold/palladium produced 25 {angstrom} grains with the thinnest continuous film at 18 {angstrom} thickness.

• Research Organization: Los Alamos National Lab., NM (United States)
• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: W-7405-ENG-36
• OSTI ID: 463601
• Report Number(s): LA-UR--96-4597; CONF-970585--1; ON: DE97003095
• Country of Publication: United States
• Language: English

Related Subjects

40 CHEMISTRY
55 BIOLOGY AND MEDICINE
BASIC STUDIES
BIOLOGICAL MATERIALS
COMPARATIVE EVALUATIONS
CYTOLOGICAL TECHNIQUES
ELECTRON MICROSCOPES
ELECTRON MICROSCOPY
GOLD
IRIDIUM
MOLECULAR STRUCTURE
MOLECULES
PLATINUM
SAMPLE PREPARATION
THIN FILMS