Chan, K. K.Pershan, PeterSorensen, L. B.Hardouin, F.2013-03-011985Chan, K. K., Peter S. Pershan, L. B. Sorensen, and F. Hardouin. 1985. X-ray scattering study of the \(smectic-A_1\) to \(smectic-A_2\) transition. Physical Review Letters 54(15): 1694-1697.0031-90071079-7114http://nrs.harvard.edu/urn-3:HUL.InstRepos:10357693X-ray scattering measurements are reported for critical \(smectic-A_2\) fluctuations along a line of second-order transitions between the \(smectic-A_1\) and \(smectic-A_2\) phases in mixtures of hexylphenyl cyanobenzoyloxy benzoate \((DB_6)\) and terephthal-bis-butylaniline (TBBA). The measured exponents \(\gamma = 1.46 \pm 0.05\) and \(\nu_{\parallel} = \nu_{\perp}= 0.74 \pm 0.03\) are constant along the second-order line and agree with recent heat-capacity measurements and the scaling law, \(3\nu + \alpha =2\). They disagree with current theoretical expectations.en-USJournal Article2013-03-0110.1103/PhysRevLett.54.1694