Sentence:  In the <WSD>gas</WSD> phase , with * * f of * * f and * * f of * * f , quantum yields of the order of * * f have been observed at 85 ` . 
Meaning of the word marked with <WSD> tags:  the state of matter distinguished from the solid and liquid states by: relatively low density and viscosity; relatively great expansion and contraction with changes in pressure and temperature; the ability to diffuse readily; and the spontaneous tendency to become distributed uniformly throughout any container