Does light absorption result in a momentarily weaker bond? I may have just misunderstood the topic, but light absorption by a molecule is a result of a promotion of an electron into an empty antibonding orbital; hence, does that mean that the strength of the bond is momentarily weakened by absorption of light? What processes account for the actual radiation part (release of heat) associated with the absorption of light? 

http://www.chemguide.co.uk/analysis/uvvisible/bonding.html
it may happen but it is not always necessary as 1S antibonding molecular orbital is lower in energy as compared to 2S bonding MO If electron jumps from 1S ABMO to 2S BMO  then BOND ORDER willhence bond will become stronger increase σ(1s) &lt;σ∗(1s) &lt; σ(2s) &lt;σ∗(2s) &lt; π(2px) = π(2py)