April 2, 2001

Show and Tell Time in the Lab

• Perkin Elmer 1440
• three gratings on a turret
• dual beam with a chopper (15 Hz?)
• reference beam automatically attenuated
• motor driven, servo system
• linked directly to pen drive
• can see grating rotate
• stop, see filters changed (overlapping orders)
• stop, gratings changed
• detector = small solid state device
• older thermocouple detector

Dye Laser System

• designed for a pulsed N2 laser (optically pumped)
• special feature-- pump laser split (40%, 60%)
• The 40% goes into a dye cell, excites dye
• dye cell in cavity
• one mirror is tunable grating
• output is a narrow band, tunable light pulse
• The 60% goes into another dye cell
• excites that dye
• this dye acts more like a true amplifier
• first dye laser beam passes through, greatly amplified
• pulse duration-- as short as pump beam (<1 nsec)

Fluorescence Lifetime with N2 Pulsed laser

• Electrical Discharge in N2 --> N2*
• Narrow channel of excited medium, lases
• Pulse is 337 nm (UV)
• We use to excite a fluorescent sample
• monochromator selects emitted light at 90o
• PMT detects
• digital oscilloscope collects data
• (built in ACD, as short as 0.5 nsec/point)

Spectrofluorimeter

• Dual monochromator system
• Strong light source, with UV (Xe arc)
• irradiate sample as excitation wavelength
• measure fluorescence at the emission wavelength
• the excitation spectrum
• what incoming wavelength produces fluorescence
• the emission spectrum
• what wavelengths are emitted by the sample

Miniature Diode array spectrometer

• Ocean Optics
• 2000 element array
• diode array on exhibit (microscope)
• fiber optics input

Mass Spectrometer

• 60o magnetic sector unit
• permanent magnet
• ion source (electron impact)
• electron multiplier

Scanning UV-Vis Spectrometer

• Beckman Acta-M-IV
• dual beam, choppers

ATR -- IR Accessory