Rick Smalley

Magnetic Pulsed Valve

Hole for the laser pulse

Graphite Laser Helium Laser pulse creates a 10,000 o carbon plasma

Nozzle Plasma Skimmer hole Mass Spectrometer

The very sharp edged skimmer skims the expanding pulse into a very narrow beam Supersonic Expansion into the vacuum chamber cools the clusters to very low temperatures

Skimmer action more slowly

Rick Smalley at Rice University in Texas had developed a laser vapourisation technique to make metal clusters Aluminium

● ● ● ● ● ● ● I suggested that if we replace the metal by graphite …as the carbon atoms react I expected them to form linear carbon chains ● ● ● ● ● ● ●

Harry Kroto 2004 H−C≡C−C≡C−C≡NH−C≡C−C≡C−C≡N H−C≡C−C≡NH−C≡C−C≡N H−C≡C−C≡C−C≡C−C≡NH−C≡C−C≡C−C≡C−C≡N

..and so simulate the conditions which produced the carbon chain molecules in the carbon rich Red Giant Star IRC 10216

Graphite Laser Helium Laser pulse creates a 10,000 o carbon plasma

The plasma pulses fly across the vacuum chamber …add the signals from many plasma pulses – say 100

Pulsed UV Laser TOF-MS Time of Flight Mass Spectrometer

Hintenberger Franzen and Schuy Z Nat 1963 Mass spectrum of arc discharged graphite

H−C≡C−C≡C−C≡C−C≡NH−C≡C−C≡C−C≡C−C≡N

Circumstellar Molecule Abundances Agúndez et al Carbon Chains in TMC1 HC 5 N HC 7 N HC 9 N HC 3 N

The Huckel 4n+2 rule predicts carbon rings with electrons should show “aromatic” character ie In the positive ion mass spectrum C 11 + C 15 + C 19 + and C 23 + Should be strong

Strong Weak

Idea was to create a carbon plasma blown out of a carbon star

Silicon disk Laser Helium Replace the silicon disk by graphite (carbon) Carbon disk

Silicon disk Laser Helium Laser pulse creates a 10,000 o atomic plasma

Silicon disk Laser Helium Laser vapourisation supersonic nozzle developed by Rick Smalley

…and produce the molecules we had detected by radioastronomy

Try to simulate the conditions in the laboratory

Graphite

Perhaps changing the disk to graphite and adding say NH 3 to the buffer gas would produce HC 7 N etc Graphite

Try to reproduce the stellar plasma in the laboratory Plasma in lab Exploding Star

Silicon Carbide had produced SiC 2 which had been detected in stellar spectra SiC