X-Ray Study of the Nematic Phase and <span class="aps-inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="normal">Smectic</mi><mo>−</mo><mrow><msub><mrow><mi>A</mi></mrow><mrow><mn>1</mn></mrow></msub></mrow><mo>−</mo><mi mathvariant="normal">to</mi><mo>−</mo><mi mathvariant="normal">Smectic</mi><mo>−</mo><mrow><mrow><mover><mrow><mi>A</mi></mrow><mrow><mi>̃</mi></mrow></mover></mrow></mrow></math></span> Phase Transition in Heptylphenyl Nitrobenzoloxybenzoate (DB7N<span class="aps-inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi mathvariant="normal">O</mi></mrow><mrow><mn>2</mn></mrow></msub></mrow></math></span>)

C. R. Safinya; William A. Varady; L. Y. Chiang; P. Dimon

doi:10.1103/PhysRevLett.57.432

X-Ray Study of the Nematic Phase and $Smectic - A_{1} - to - Smectic - \tilde{A}$ Phase Transition in Heptylphenyl Nitrobenzoloxybenzoate (DB7N $O_{2}$ )

C. R. Safinya, William A. Varady, L. Y. Chiang, and P. Dimon

Phys. Rev. Lett. 57, 432 – Published 28 July 1986

Abstract

We report a high-resolution x-ray study of the fluctuations in the nematic and smectic- $A_{1}$ phases in heptylphenyl nitrobenzoloxybenzoate. As a function of decreasing temperature, the fluctuations evolve from an incommensurate region, through an intermediate region of coexisting (competing) incommensurate and smectic- $\tilde{C}$ fluctuations, to a region dominated by pretransitional smectic- $\tilde{A}$ fluctuations which exhibit a phase-lockin $smectic - A_{1} - smectic - \tilde{A}$ transition. This behavior directly confirms the current theoretical description of the smectic- $\tilde{A}$ and smectic- $\tilde{C}$ phases as alternatives to the incommensurate phase.