Drear Mukesh,

In order to convert the wavelength lambda int photon energy Eph then you use the formula

Lambda= hc/Eph= hc/ q Vph,

h is the planck's constant,

c is the speed of light

q the electron charge

Vph is the photon energy in eV

Lambda in nm= Lambda x 10-9

Best wishes

Drear Mukesh,

In order to convert the wavelength lambda int photon energy Eph then you use the formula

Lambda= hc/Eph= hc/ q Vph,

h is the planck's constant,

c is the speed of light

q the electron charge

Vph is the photon energy in eV

Lambda in nm= Lambda x 10-9

Best wishes

Dear Mukesh,

To convert the wavelength lambda int photon energy (Eph) in eV you can use the following direct valid approximation :

Eph= 1240/(wavelength in nm)

Good luck

I fully agree with Professor Abdelhalim

Thanks for the short and wonderful answer

Thanks Professor Abdelhalim

According to your suggested formula the unit is kW m-2 but i want it from

kW m-2 nm-1 to kW m-2 eV-1, so i make square of Vph.

so the formula is correct or not ?

P1( hc/ q Vph Vph)=P2

where,

h is the planck's constant,

c is the speed of light

q the electron charge

Vph is the photon energy in eV

P1 is spectral irradiance (unit = kW m-2 nm-1)

P2 is spectral irradiance (unit = kW m-2 eV-1)

Note:- i want to calculate P2 the methods i used is correct ?

Thanks in advance

Dear Mukesh,

I meant to substitute for lambda in nm in the denominator of your unit by the formula which i brought to you.

Assume that your quantity in w/m^2 nm is = P then to convert it to w/ m^2 eV you have to divide it by Lambda in nm which i brought you in the prevous comment

That is

Pnew= P /( hc/ q Vph x10^-9)= (P q Vph x10^-9) / hc

Best wishes