[Absorption spectra study of cation surfactant-[AuI4]- association particle system and its analytical application].

In 0.01 mol x L(-1) HCl medium, there is an absorption peak at 350 nm for [AuI4]-. The association particle system of CTMAB-[AuI4]- exhibits violet-red color. It has a new absorption peak at 520 nm. The CTMAB concentration cCTMAB in the range of 0-7.0 x 10(-5) mol x L(-1) is linear to the A(520 nm) value. Its regression equation is A(520 nm) = 0.989 x 10(4) cCTMAB + 0.0138, regression coefficient is 0.9995, and the mole absorption coefficient is 1.059 x 10(4) L x mol(-1) x cm(-1). A new spectrophotometry has been proposed for the determination of cation surfactant. The resonance scattering spectra show that the CTMAB+ and [AuI4]- combine to form (AuI4-CTMAB) association molecule with hydrophobicity by means of attraction forces. The association molecules automatically aggregate to form (AuI4-CTMAB)n association particles. So, the particles exhibit two resonance scattering peaks at 580 and 470 nm, and the system exhibits violet-red.