The viability of pulsed laser photofragment emission (PFE) is evaluated for the in situ measurement of vapor-phase mercuric chloride \left({\text{HgCl}}_{\text{2}}\right) concentration in combustion flue gas. Dispersed emissions from both the \text{Hg}\left(\text{6}{}^3{P}_1\right) and \mathrm{HgCl}\left(B{}^2{\mathrm{\Sigma }}^{+}\right) photoproducts are presented, and the dependence of the {\text{HgCl}}_{\text{2}} PFE signal originating from \text{Hg}\left(\text{6}{}^3{P}_1\right) on the collisional environment is examined for buffer-gas mixtures of {\text{N 2}}_{} , {\text{O 2}}_{} , and {\text{CO}}_{\text{2}} . Integrated PFE intensity measurements as a function of buffer gas pressure support the assumption that the primary effect of the relevant flue gas constituents is to quench emission from \text{Hg}\left(\text{6}{}^3{P}_1\right) . The quenching rate constants for PFE from {\text{HgCl}}_{\text{2}} were measured to be 1.37\left(\pm 0.16\right)\times {10}^5{\text{Torr}}^{-1}{\text{s}}^{-1} for {\text{N 2}}_{} , 9.35\left(\pm 0.25\right)\times {10}^6{\text{Torr}}^{-1}{\text{s}}^{-1} for {\text{O 2}}_{} , and 1.49\left(\pm 0.29\right)\times {10}^6{\text{Torr}}^{-1}{\text{s}}^{-1} for {\text{CO}}_{\text{2}} . These values are in good accord with literature values for the quenching of \text{Hg}\left(\text{6}{}^3{P}_1\right) . The emission cross section for \text{Hg}\left(\text{6}{}^3{P}_1\right) generated by photodissociation of {\text{HgCl}}_{\text{2}} in 760\text{\hspace{0.17em} Torr \hspace{0.17em}}{\text{N 2}}_{} is found to be 1.0\left(\pm 0.2\right)\times {10}^{-25}{\text{m 2}}^{} by comparing the PFE signal to {\text{N 2}}_{} Raman scattering.