Impact of Surface Symmetry on Growth-Induced Properties

Abstract

The influence of surface symmetries on growth-induced physical properties is studied. Three processes for which this impact is particularly significant are reviewed: (i) adsorption of chiral molecules on solid substrates, (ii) symmetry reduction due to adsorption of impurities during growth, and (iii) self-poisoning during growth. It is shown that surface symmetries may propagate to the entire growth sector, leading in case of (ii) and (iii) to a crystal composed of domains with different chemical compositions and physical properties. As an example, growth-induced pyroelectricity due to self-poisoning is systematically studied for the most representative faces of the 32 point groups. It shows that the knowledge of surface symmetries may help in the control and design of growth-induced properties. Finally, necessary steps toward the qualitative and quantitative prediction of growth-induced properties are proposed.

Achiral Organic, Inorganic, and Metal Crystals as Auxiliaries for Asymmetric Transformations

“…The occurrence of reduction in symmetry has also been recorded in centrosymmetric crystals displaying atomic or molecular disorder. Thus for example, Gervais and Hulliger16 have demonstrated that p ‐nitro‐ p ′‐chloro‐stilbene, which crystallizes in point group 2/ m , was demonstrated to form enantiomorphous sectors, as a result of disorder, where the Cl and the NO 2 groups interchange in certain sectors of the crystal such that they convert the centrosymmetric crystal into a conglomerate of polar sectors. The reduction in symmetry in some of the sectors of this centrosymmetric crystal has been determined also by the display of pyroelectric effect in certain directions of the sector.…”

Polar Vector Property of the Stationary State of Condensed Molecular Matter

“…Considering real crystal structures, e.g., nucleation processes leading to n/m (n = 2, 3, 4, 6) point groups and growth along the axis n, the stochastic process transforms pro-chiral faces into chiral sectors. Because of the mirror plane m passing through a seed, sectors involving the +n or the −n direction show an enantiomorphic relation (for a discussion of other point groups and low index faces, see [22]). …”

Dissymetrization of molecular crystals: a driving force for property formation

“…Neumann's principle gives thought to physical properties of bulk crystals [2], although building blocks undergo attachment to surfaces confined to 2D point groups. For growth induced properties, Neumann's principle may thus be restated as follows [3]: The symmetry elements of a physical property of a growth sector include all symmetry elements of the point group of the growth sector. Properties resulting explicitly from processes at the crystal-nutrient interface are those, which in principle should disappear if thermalization of the bulk structure far off the surface has reached the minimum of free energy.…”

“…Explicitly, a symmetry analysis for a vector property, i.e. pyroelectricity was performed [3].Here, we shall understand dissymetrization as a constructive phenomenon for physical property formation. Vector property formation is particularly interesting in the case of molecular crystals, constituted by prolate shaped dipolar molecules.…”

“…Vector property formation is particularly interesting in the case of molecular crystals, constituted by prolate shaped dipolar molecules. After an extensive experimental [9][10][11][12] and theoretical [3,[13][14][15][16][17][18][19][20][21][22][23] analysis starting in 1995, we are about to conclude that any dipolar molecule crystallizing into a crystal structure described on average by a non-polar point group undergoes (to some extent) sector-wise dissymetrization, leading to sectors showing polar properties. Growth-induced polarity formation leads to non-classical twinning, i.e.…”