Question

Please briefly answer all the questions below ,and writing those more clearer and tidier (It is best to use typing)

1. This is a problem related to the spectroscopy.
   1. Please describe two different spectroscopic methods that use lasers as the light source.
   2. Applying conventional spectroscopy to nanoscale research usually suffers with low signal-to-noise ratio. Can you describe the practice(s) being used to overcome this difficulty and explain why it works?

Answer 1

1) Photoluminescence Spectroscopy - To find out the electronic structure of materials

2) Raman Spectroscopy- Based upon the inelastic scattering of laser and studying the sample by analyzing the transitions in their vibrational levels. Intensities of Raman lines are very low hence very good detector is needed which can detect this small change in energy occuring due to inelastic scattering.

Both of these spectroscopies use laser as source of incidence.

Main source of error- Detector is always the main source of error. (Like in photo multiplier tube, charge is collected in the end which gives the information of energy. All nuclear processes are statistical in nature means always having a delta variation giving rise to FWHM. Background counts are also the same kind of thing arising due to low energy transitions involved.)

Also if sample is not prepared well that will also give noise like in case of thin film if the film is non-uniform.

Error Removal- As the main source of noise is the detector so many algorithms are used to overcome this like slow scanning of sample so that detector gets enough time to collect the required information and many more.

Plz comment regarding any query . May be I ll help as I work on these systems.