Wyatt and Klier reply:

Abstract

Wyatt and Klier reply: In our Letter [1] we drew attention to the fact that the metastability of thick helium films on quench-condensed Cs substrates was not resolved. The situation is more complicated than the metastability expected for a first order wetting transition on a perfect substrate. This is clear from the fact that dry holes can be created in the helium films by a laser pulse and these holes do not expand causing the Cs to dry [2]. This shows that the thermal nucleation problem is irrelevant and that the pinning of the contact line is crucial. We also addressed the surprising phenomenon that these same Cs surfaces show a memory effect; that is, once the surface has been flooded with liquid helium and then the surface has apparently dried, a subsequent flooding only flows out to the previous flooded boundary. We proposed that stable micropuddles on a rough Cs surface could explain both the strong pinning of the contact line and the memory effect.We did not comment on the liquid on liquid system as it has no bearing on the problem of quench-condensed Cs. These Cs substrates are rough compared to a liquid, and it is the roughness that causes the pinning and makes their behavior not ideal. We showed that micropuddles on a rough surface can be thermodynamically stable. This is important for a long term memory effect. Stability is achieved by having pressure differentials between the vapor and the liquid in the micropuddle due to surface tension and van der Waals forces. The pressure differential across the free liquid surface is given by p 2 p 0 2s ly ͞R, and there is no conflict as suggested by Bonn et al. [3]; on the contrary, it is consistent and necessary.We drew an explicit distinction between cavities that can be filled by flooding and by capillary condensation. One of the new aspects in our paper was that micropuddles can form only by flooding. We envisage that cavities on thin Cs films are shallow and do not fill from the vapor phase. There is no evidence or suggestion that capillary condensation occurs on these Cs surfaces.Bonn et al. [3] suggest that the quench-condensed Cs surface is so extremely rough that it is "a spongelike porous medium" with connected liquid channels. We had not thought that most quench-condensed Cs were as bad as this. If it is, then the contact angle measurements made on them are profoundly modified by the surface topography and have little resemblance to the contact angle on a smooth surface. It is very misleading of Bonn et al.[3] to use these low values of the contact angle in their estimates of the pinning energies. Also such a surface invalidates the applicability of any theory that assumes a plane surface, such as the one referred to in their second paragraph. It seems unlikely to us that a connected filamentary superfluid film on a rough two-dimensional substrate can explain the memory effect. However, if such a film becomes disconnected, then it is similar to an extended micropuddle. The liquid isolation of the micropuddle is necessary for 279602-1 0031-9007͞01͞ 87...

Reconciling semiclassical and Bohmian mechanics. III. Scattering states for continuous potentials

“…Thus, for a two-term or "bipolar" decomposition, ⌿ = ⌿ 1 + ⌿ 2 . This rather trivial-seeming procedure can be quite advantageous in the context of quantum trajectory methods ͑QTMs͒, [4][5][6][7][8][9][10][11][12][13] i.e., trajectory-based numerical techniques for performing exact quantum dynamics calculations, based on Bohmian mechanics. [14][15][16][17][18][19] Conventional QTMs use a single-term or "unipolar" representation of the wave function from which all other quantities, such as the quantum trajectories themselves, are uniquely determined.…”

Accurate calculations of reaction rates: predictive theory based on a rigorous quantum transition state concept

“…Using the specific properties of the flux operator [26] to avoid tracing over the reaction coordinate can not really solve this problem: considering a f-dimensional problem tracing with respect in the other (f-1) coordinates still has to be done. Consequently, early quantum calculations using flux correlation functions [26][27][28][29][30][31][32][33][34][35][36][37][38] were restricted to systems not exceeding three atoms.…”

Three-dimensional quantum mechanical studies of the H + H2 and F + H2 reactions

“…is obtained. A surprisal and entropy analysis of the H + H, react; e rotational distribution at a higher energy is reported elsewhere [22]. It should be emphasized that the linearity of the surprisal plots was in no way forced on the system.…”