Spectroscopy Parts 3 and 4 Flashcards
What is the correct order of the parts of a single-beam instrument?
Light source → λ selector → Sample cell →Photo-detector → Electronics, computers
What emits radiation in the visible light source: Tungsten-halogen lamp?
Visible and NIR radiation (ca. 350-2500 nm)
What emits radiation in the UV light source: Deuterium lamp?
Mostly UV radiation
What is the most commonly used spectrophotometric components for variable wavelength selection?
Reflection gratings
What is the difference between constructive and destructive interference?
Constructive interference: when two wavelengths are added and they form a more intense wave
Destructive interference: when two wavelengths are added and they produce a single line
What is the order of the indispensable components of a monochromator?
slit → grating → slit
What determines the monochromator bandwidth?
Entrance and exit slit widths
Why do we want a narrow bandwidth?
To see spectrodetails
Define Dispersion
The angular spread of diffracted wavelengths increases as the groove density (lines per millimeter) increases. Resolution increases, working range decreases
What do double monochromators do?
Reduce stray light by orders of magnitude
What is the purpose of the slit, sine bar, mirror, grating?
What is the basic layout for double monochromators?
Entrance slit → Grating → Slit → Grating → Exit slit
What are the two important points for Cuvettes and Spectrophotometer cells?
Must provide a defined and reproducible path length and must be transparent to wavelength range of interest
What are microtiter plates?
Plates that give fast and high-throughput analysis
What is PMT?
Photomultiplier tube
