How is the total molecule energy composed?
nucleus-, electric-, vibrational-, rotational-, translatoric Energy
How can vibrations of a molecule be described?
By decomposition in vibrational modes
Each vibrational mode is its own harmonic oscillator
What part of a material absorbs infrared waves?
The bindings between atoms are exited and vibrate. The frequency is characteristic for a binding.
What are the regions of IR radiation in wavevector k?
How many degrees of freedom do molecules have?
For what stands FTIR?
Fourier transformed InfrarRed spectoscropy
Why is there an interferometer used in FTIR analysis?
To be able to conduct a fourier transformation and do the process in one step <=> create a Interferogram <=> include all the wavelengths of the source
What are the steps in an FTIR analysis?
Create Interferogram
run Interferogramthrough sample
detect changed Interferogram
conduct fourier analysis and compare it to initial spectrum
obtain the absorbed wavelengths
What are the advantages of a FTIR analysis?
simultainious detection of whole spectrum
good signal to noise ratio
improved accuracy and reproduceabiliy
How are liquid samples stored?
Cells with KBr or NaCl windows (important that infrared transmitting)
How are solid samples stored?
fine dispersion in KBr
films
What is Attenuate Total Reflectance (ATR)?
The use of a reflective body to analyse non transparent materials in infrared spectroscopy.
The waves can penetrate into the material with a depth similar to the wavelength. (0.5-2µm)
What are source materials for FTIR?
ceramic sources
rare earth oxides
What are FTIR detectors?
semiconductors
thermal detectors
Which information can be obtained from FTIR spectra?
compostion and types of functional groups
chain structure
degree of branching
nature of organic, nonorganic interaction
processing effects
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