Biology
Linac Coherent Light Source

Fixed Targets

Sample Delivery

A common way to deliver a sample to an instrument is to hold the sample to the interaction area or have a fixed target. Familiarity with synchrotron mesh loops, pin mounts, and synchrotron goniometers or cryoEM metal grids helps to understand this method.

 

Pros and Cons of Fixed Targets

Pros Cons Ideal For
  • Minimal concerns with fluid/slurry properties (no clogging, high viscosity, etc.)
  • Compatible with some time-resolved experiments (e.g., pump-probe)
  • No wasted samples in between pulses if synchronized and sample locations are known

 
  • Difficult to mount sample onto substrate
  • Complicated in-vacuum operation
    • Prohibitive in-vacuum machinery
    • Need to account for vacuum effects on samples awaiting inspection
    • Time-consuming to replace sample-loaded substrates
  • Can’t match faster pulse structures
  • Need to know sample locations on substrate
  • Contribute to background signal from substrate Incompatible with other time-resolved experiments (mixing, complex/multiple pump probes)
  • Large samples (>50 μm)
  • Low sample quantity
  • Experiments that don’t require vacuum conditions
  • Delicate samples that can't handle pressures of liquid injection (high solvent, low lattice contacts, 2-D crystal plates)