Chemical Dynamics Study of Intrasurface Hydrogen-Bonding Effects in Gas−Surface Energy Exchange and Accommodation

Abstract

Classical chemical dynamics simulations were performed to compare the efficiency of energy transfer in collisions of Ar with 300 K CH3- and OH-terminated alkyl thiol self-assembled monolayer surfaces (i.e., H-SAM and HO-SAM) and compare with previous experiments (Anal. Chim. Acta 2003, 496, 249). The experiments show that energy is transferred less efficiently to the HO-SAM. The H-SAM has a periodic, ordered surface structure, whereas the surface of the HO-SAM has a disordered, “glassy” structure as a result of “clustering” of the terminal OH groups. The Ar atom has a much stronger physisorption interaction with the HO-SAM, arising from the strong Ar···O van der Waals interaction. Though the simulations show that physisorption is more important for Ar atoms colliding with the HO-SAM, energy transfer is less efficient to this surface. The latter results from a significant difference in the energy transfer for direct collisions with the two surfaces. More energy is deposited in the H-SAM for direct collisions. This difference appears to arise from enhanced efficiency to excite interchain intermolecular modes for the H-SAM as compared to the HO-SAM. The OH-group clustering enhances surface rigidity and decreases the efficiency of exciting intermolecular modes in direct collisions of Ar atoms with the HO-SAM. Overall, the energy transfer efficiencies determined from the simulations are in excellent agreement with experiment. The simulations suggest that the so-called trapping desorption (TD) component of the experimental translational energy distribution, for Ar + H-SAM scattering, actually consists of both physisorption and direct trajectories.

A Molecular Dynamics Study on Heat Transfer Characteristics Over the Interface of Self-Assembled Monolayer and Water Solvent

“…2(a)). Especially in the OH-terminated SAM system, it was reported that terminal OH groups form a network structure in the surface plane due to hydrogen bonding [29], which is likely to be susceptible to potential models. 2(b)).…”

Mechanistic details of energy transfer and soft landing in ala2-H+ collisions with a F-SAM surface

“…10,11 For low collision energies the ion may adsorb on the surface intact, with or without charge retention, a process referred to as SL. [28][29][30][31][32][33][34][35][36][37][38][39][40][41]45 Energy transfer probabilities to the surface and projectile may be determined, [28][29][30][31][32][33][34][35][36][37][38][39][40][41]45 as well as features of the collision such as the importance of surface penetration 29,[33][34][35][36]41,46,47 or physisorption. 13 SL and RL have numerous uses, [12][13][14][15][23][24][25]42 including preparation of protein or peptide a...…”

Dynamics of the Reaction of O(3P) Atoms with Alkylthiol Self-assembled Monolayers

“…[5][6][7] Fairbrother and co-workers have also examined the destruction of alkyl, fluorinated, and X-raymodified SAMs by a thermalized mixture of atomic and molecular oxygen (O( The first such experiment was carried out by Naaman and coworkers 10 using molecular beams of He, Ar, NO, and O 2 from alkyl and fluorinated SAMs and time-of-flight mass spectrometry (TOF-MS) to detect the scattered species. Subsequent work by Siebener and co-workers [11][12][13][14][15] and, most comprehensively, by Morris and co-workers [16][17][18][19][20][21][22][23][24][25][26] has investigated the effects of varying the identity of the impinging gas, impact angle, final angle, initial energy, monolayer temperature, SAM terminal group, alkyl chain length, and metal substrate (hence, surface density). This has led to a wealth of information on factors affecting energy transfer at the gas-SAM interface.…”