Transmitted light Brightness = fn (NA2 / magnification2)ġ0x 0.5 NA is 3 times brighter than 10x 0.3NAĮpifluorescence Brightness = fn (NA4 / magnification2) 10x 0.5 NA is 8 times brighter than 10x 0.3NA Optimize light collection, uniformity of illumination Pumps more dye into the triplet state (reactive oxygen and silent) Noise doesn’t saturateĪutofluorescence in cell flavins, NADH, NADPH Raman spectrum of water To reduce bleaching: Shorten Triplet lifetimeĪntibleach Agents: Retinoids, carotinoids, glutathione Vitamin E, N-propyl gallateĮliminate Oxygen (scavenger, bubble N2) No reactive oxygen produced (but lengthens triplet lifetime)Ĭan’t get more light by turning up the laser: Dye saturates as I is increased Intense laser beam depletes dye in ground state ~ lifetime of a dye Given dwell-time of laser beam, ISC, collection efficiency Lucky to record 1 photon/dye/scanĮvery emitted photon is sacred! Maximize throughput (filters, lenses, mirrors) Minimize Bleaching Not enough fluorescence photons? If >200 photons/ pixel needed Microscope records 0.02% Need about 100,000 photons/pixel Triplet state lifetime shortened by oxygen (20msec if none 0.1 usec if oxygen present Good news: Returns dye to ground stateĪside: Phosphor Imager ISC High probability Very slowĮxcited triplet state Phosphorescence (very slow)Īccumulate triplet state (thermally stable) “read out” with scanning red laser Gives energy for transition to singlet state Emission of light proportional to the stored triplet Interstate Crossing (ISC) Problem 2: Reactive oxygen ISC ~0.03
A manual dropper is used to insert dust into the plasma. Argon gas is admitted into the chamber by an MKS mass flow meter and pumping is regulated by a butterfly valve to set pressure for experiments. It is pumped on by one of two Oerlikon turbo pumps with a pumping rate of 1100 l/s or 270 l/s. A 0.85 m diameter plate in about the center serves as a powered electrode (13.56 MHz) with the chamber walls as the ground.
The vacuum chamber is a stainless steel cylinder 0.90 m in diameter and 0.34 m in height with ports for viewing and measurement. The Complex Plasma Research Group at the German Aerospace Center (DLR) in Oberpfaffenhofen has built a new large diameter rf plasma setup for dusty plasma experiments.