Detectors (UV-Vis) 1. Phototube 2. Photomultiplier Tube (PMT) 3. Si Photodiode 4. Photodiode Array (PDA) 5. Charge Coupled Device (CCD) 6. Charge Injection Device (CID)

1. Phototube 200 – 1000 nm 1-10 ns response time 0.01 A/W

2. Photomultiplier Tube (PMT) 110 – 1000 nm 1-10 ns response time 10,000 A/W

2. Photomultiplier Tube (PMT)

3. Si Photodiode Si: 3s 2 3p 2 Covalent Bonds in Solid Therefore 1/2–filled sp3 ΔE ≤ 2.5 eV (semiconductor) 4 electrons fill a valence band at 0K At higher T an electron can move to conduction band Leaving a positive hole behind (both are mobile)

3. Si Photodiode Doping Si with a group 5 element (As or Sb) results in extra electrons (n-type). Doping with a group 3 element (In, Ga) results in extra holes (p-type)

3. Si Photodiode

Forward bias (not very useful for spectroscopy)

3. Si Photodiode Reversed Bias: Depletion zone at the junction. Photons may eject electrons and form holes Current proportional to number of photons

3. Si Photodiode 200 – 1000 nm 1-10 ns response time 0.05 A/W

4. Linear Photodiode Array 200 – 1000 nm 1-10 ns response time 0.05 A/W

4. Linear Photodiode Array

5. Charge Coupled Device (CCD) 200 – 950 nm 1-10 ns response time A/W

5. Charge Coupled Device

6. Charge Injection Device (CID)

Detector Responsivity R(λ) =Current Output (A) Incident Power (W) Gain of the Signal Modifier G =Output Potential (V) Input Current (A)