In the fluorescence quenshing of rhodamine B dye, the fluorescence decay of rhodamine B in the DMF-solution with ethanol-water mixture was monitored by measureing the 605 nm emission lifetime (decay of intensity over time) after a laser pulse. The lifetime () of the rhodamine B in absence of quenchers is 2.10 ns. Quenshing of rhodamine fluorescence by the presence of 2% ethanol-water mixture reduced the lifetime () to 1.86 ns. Using the following Stern-Volmer equation, what would be the rhodamine B emission lifetime in ns by changining the ethanol water to 9%?

The ratio of the fluorescence lifetime in the absence and in the presence of a quencher is given by

This equation is used to produce a Stern-Volmer plot, in this plot

A.

the lifetime ratio (0/) versus concentration quencher [Q] has a slope = kq

B.

the lifetime ratio (0/) versus concentration quencher [Q] has an intercept = 1

C.

the intensity (I 0/I) versus concentration quencher [Q] has an intercept = kq/k1

D.

the intensity (I 0/I) versus concentration quencher [Q] has an intercept = ( k1+ k2)

E.

the lifetime ratio (0/) versus concentration quencher [Q] has a slope = kq/k1