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Rick Smalley. Magnetic Pulsed Valve. Magnetic Pulsed Valve. Magnetic Pulsed Valve. Hole for the laser pulse. Laser. Laser pulse creates a 10,000 o carbon plasma. Helium. Graphite. Skimmer hole. Nozzle. Mass Spectrometer. Plasma.
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Laser Laser pulse creates a 10,000o carbon plasma Helium Graphite
Skimmer hole Nozzle Mass Spectrometer Plasma
Supersonic Expansion into the vacuum chamber cools the clusters to very low temperatures The very sharp edged skimmer skims the expanding pulse into a very narrow beam
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 ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ●
H−C≡C−C≡N H−C≡C−C≡C−C≡N H−C≡C−C≡C−C≡C−C≡N Harry Kroto 2004
..and so simulate the conditions which produced the carbon chain molecules in the carbon rich Red Giant Star IRC 10216
Laser Laser pulse creates a 10,000o carbon plasma Helium Graphite
The plasma pulses fly across the vacuum chamber …add the signals from many plasma pulses – say 100
TOF-MS Time of Flight Mass Spectrometer Pulsed UV Laser
Hintenberger Franzen and Schuy Z Nat 1963 Mass spectrum of arc discharged graphite
Carbon Chains in TMC1 HC3N HC5N HC7N HC9N Circumstellar Molecule Abundances Agúndez et al
The Huckel 4n+2 rule predicts carbon rings with 6 10 14 18 22 electrons should show “aromatic” character ie In the positive ion mass spectrum C11+ C15+ C19+ and C23+ Should be strong
Strong 11 15 19 23 Weak 13 17 21 25
Idea was to create a carbon plasma blown out of a carbon star
Laser Replace the silicon disk by graphite (carbon) Helium Silicon disk Carbon disk
Laser Laser pulse creates a 10,000o atomic plasma Helium Silicon disk
Laser Laser vapourisation supersonic nozzle developed by Rick Smalley Helium Silicon disk
…and produce the molecules we had detected by radioastronomy
Perhaps changing the disk to graphite and adding say NH3to the buffer gas would produce HC7N etc Graphite
Plasma in lab Exploding Star Try to reproduce the stellar plasma in the laboratory
Silicon Carbide had produced SiC2 which had been detected in stellar spectra SiC