Investigation of optical pumping for binary mixtures may provide information on the interaction between atomic systems and open up possibility to control response time.Considered Rb isotope

85

Rb and

87

Rb as binary mixtures

optical pumping response can be observed with using square modulated field at 10Hz and two channels of RF sources for NMR of

85

Rb and

87

Rb respectively.Based on proposed model of three energy levels

unitary system or binary mixtures of

85

Rb and

87

Rb can be accurately described with an exponential function.According to the relation of response time between binary and unitary

the response time for mixtures is contributed from unitary ones and their concentrations.