Black-body radiation spectral analysis

[mic*]

Why is it that we observe a continuous spectrum in black-body radiation not discrete spectral lines dependent on the composition of the black-body?

A niave understanding is that it relates to the complexity of the atomic structure of the black-body as well as thermal motion of its constiuent atoms. Due to these factors the emission lines become less distinct and meld into one continuous spectrum.

Could somebody please elaborate on this, or otherwise correct the above statement.

 

[WannabeNewton]

That property of the energy spectrum of an ideal photon gas in a blackbody can be derived using equilibrium thermodynamic arguments on the radiation field. More specifically, one appeals to the principle of detailed balance.

See: http://books.google.com/books?id=BC... detailed balance blackbody radiation&f=false

 

[Bill_K]

Why is it that we observe a continuous spectrum in black-body radiation not discrete spectral lines dependent on the composition of the black-body?

Because thermal radiation arises almost entirely from the collision of atoms, not from their excitation.