In the present work we have studied the Gaussian pattern and its time evolution observed in the diffusion region separating two liquids in a Christiansen cell. It has been observed that there is a definite co-relation between the shape of the Gaussian pattern and the width of the diffusion region. When the diffusion band attains its maximum length, Gaussian pattern nearly vanishes. When laser beam is passed through this region of diffusion, a circular diffraction halo pattern has been observed.

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... The time evolution of these Gaussian patterns will throw much needed light not only on the theory of the Christiansen effect but also to develop an optical technique to measure the rate of diffusion between two molecules.