Development of a Carbon Nanotube Stripper Foil Karl von Reden and Enid Sichel Geology and Geophysics Department Presented at the Symposium of Northeastern Accelerator Personnel 2003, Strasbourg, FR

Outline Introduction: reasons for doing this State of the art in nanotube R&D Problems Our progress (so far) What is next?

Reasons for doing this Compact Accelerator Mass Spectrometry systems with accelerating voltages < 500 kV are under development. Stripper* thickness needed: 2 – 5  g/cm 2 Gas stripping requires large effort in vacuum pumping to reduce background from scattering outside of the stripper canal Characteristics of nanotubes and their (purified) aggregates might be superior to “traditional” amorphous, graphite, even diamond-like films…

State of the art in nanotube R&D “armchair” “zigzag” “chiral” STM: Venema et al., 1998 M. Daenen et al., 2003

~10 nm SWNT ropes (from R. Smalley’s group) Rinzler et al., 1998 Thess et al., 1996

Who How Typ. Yield SWNT MWNT PRO CON M. Daenen et al., 2003

Properties of single-walled carbon nanotubes (SWNT) and other forms of carbon Average diameter (nm)1.3 Length/diameter ratio»1000 Density (g/cm 3) Band gap (eV) metallic SWNT 0.0 semiconducting SWNT~0.5 Resistivity (  cm) ~ Max. Current Density (A/m 2 )10 13 N/A Thermal Conductivity (kW/m/K)~2~ Young’s Modulus (Tpa)10.01 Max. Tensile Strength (Gpa)~100~ SWNT DiamondGraphite

Problems? Homogeneity (pin holes, clusters) Required condition: Beam spot large compared to nano structure Constant average foil thickness (no taper or other macroscopic changes across the foil )

AD foil DLC foil Liechtenstein et al Thickness variability of foils (from AFM images)

Graphite foils Jeschke et al., 2001

Progress (so far) Collaborations or contacts started with Doug Chrisey, NRL “MAPLE” Facility Gary Wnek, VCU “Electro-spinning Facility” Frank Hennrich, Uni. Karlsruhe, FZK Commercial Suppliers Testing possible at Paul Skipper’s biomedical AMS Facility at MIT or at the NRL TEAMS Laboratory

MAPLE Pique, McGill, Chrisey, 2000

D. Li et al. (UW), 2003 Electro-spinning

DC glow discharge, RF glow discharge Liechtenstein et al., 1997

Laser plasma ablation deposition Maier-Komor, 1995

Laser ablation Lebedkin et al., FZK (2001)

Hennrich et al. 2002

Hennrich - 2 Hennrich et al. 2002

Commercial SWNT films

What is next? Try out Karlsruhe type film in one of the AMS labs with accessible terminals Follow SWNT R&D (mats of highly aligned few-mm-long SWNT ropes desirable) Consider other structures: Stripper canals filled with “nano wool”? This work is supported by a grant from WHOI’s “Cecil H. & Ida M. Green Technology Innovation Awards”