91影视

Electromagnetic radiation is the 鈥渇orm of energy鈥� with both electric and magnetic fields. It is generated by the sun, in which the electric field and magnetic field oscillate perpendicular.

Electromagnetic waves are of many types depending upon thetype of oscillation.

Conversion of 200 nm and 400 nm wavelength to a meter is done as follows:

$\begin{array}{c}{\text{位=200脳10}}^{\text{-9}}\text{m}\\ {\text{=2脳10}}^{\text{-7}}\text{m}\\ {\text{位=400脳10}}^{\text{-9}}\text{m}\\ \text{hence}位{\text{=4脳10}}^{\text{-7}}\text{m}\end{array}$

The energy of electromagnetic radiation of ${\text{2脳10}}^{\text{-7}}\text{m}$wavelength is given as follows:

$\begin{array}{c}\text{E=}\frac{{\text{1.20脳10}}^{\text{-4}}\text{鈥塳闯/尘辞濒}}{\text{位}\left(\text{inm}\right)}\\ \text{=}\frac{{\text{1.20脳10}}^{\text{-4}}\text{鈥塳闯/尘辞濒}}{{\text{2.0脳10}}^{\text{-7}}}\\ {\text{=6.0脳10}}^{\text{2}}\text{鈥塳闯/尘辞濒}\end{array}$

The energy of electromagnetic radiation of ${\text{4脳10}}^{\text{-7}}\text{m}$wavelength is given as follows:

$\begin{array}{c}\text{E=}\frac{{\text{1.20脳10}}^{\text{-4}}\text{鈥塳闯/尘辞濒}}{\text{位}\left(\text{inm}\right)}\\ \text{=}\frac{{\text{1.20脳10}}^{\text{-4}}\text{鈥塳闯/尘辞濒}}{{\text{4.0脳10}}^{\text{-7}}}\\ {\text{=3.0脳10}}^{\text{2}}\text{鈥塳闯/尘辞濒}\end{array}$

Therefore the energy of electromagnetic radiation in the spectral region from 200 nm to 400 nm is 300-600 kJ/mol.

The energy of electromagnetic radiation in kJ/mol for UV is 300-600, for IR is 4.8-48, and for ${}^1\mathrm{H}$NMR is $8.0脳{10}^{鈭�5}$.

Thus the energy required for UV transition is greater than for IR or ${}^1\mathrm{H}$NMR transition