Effect of alkyl chain-length on dissociative attachment: 1-bromoalkanes on Si(100)-c(4×2)

Maryam Ebrahimi; Si Yue Guo; Kai Huang; Tingbin Lim; Iain R. McNab; Zhanyu Ning; John C. Polanyi; Mark Shapero; Jody Yang

doi:10.1021/jp301773m

Effect of alkyl chain-length on dissociative attachment: 1-bromoalkanes on Si(100)-c(4×2)

Maryam Ebrahimi, Si Yue Guo, Kai Huang, Tingbin Lim, Iain R. McNab, Zhanyu Ning, John C. Polanyi^*, Mark Shapero, Jody Yang

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

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Abstract

Chemical reactivity as a function of chain-length was investigated for three 1-bromoalkanes on silicon. The physisorption and subsequent thermal dissociative attachment of bromoethane (EtBr), 1-bromopropane (PrBr), and 1-bromobutane (BuBr) on Si(100)-c(4×2) were examined by scanning tunneling microscopy in ultrahigh vacuum from 50 to 180 K, and interpreted by ab initio theory. These 1-bromoalkanes were found to physisorb and react exclusively over the inter-row sites of Si(100)-c(4×2), with activation barriers, E _a, increasing with alkyl chain-length: E _a = 343 ± 5 meV for EtBr, E _a = 410 ± 6 meV for PrBr, and E _a = 536 ± 2 meV for BuBr. Extensive ab initio calculations gave increasing barriers along the series: E _c = 317 meV for EtBr, E _c = 406 meV for PrBr, and E _c = 430 meV for BuBr. On the basis of our calculated geometries, we interpret this dependence of thermal barrier on chain-length as due to the additional energy required with increasing chain-length in order to lift the alkyl chain away from the surface, in going from the initial physisorbed state to the reactive transition state. For BuBr, the measured E _a significantly exceeded the calculated value. This increase in effective barrier-height could be due to a "dynamical delay" in optimizing the configuration of the alkyl chain.

Original language	English
Pages (from-to)	10129-10137
Number of pages	9
Journal	Journal of Physical Chemistry C
Volume	116
Issue number	18
DOIs	https://doi.org/10.1021/jp301773m
State	Published - 10 May 2012
Externally published	Yes

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@article{cd69bf90c9b44b9bb0d848d1c0650afb,

title = "Effect of alkyl chain-length on dissociative attachment: 1-bromoalkanes on Si(100)-c(4×2)",

abstract = "Chemical reactivity as a function of chain-length was investigated for three 1-bromoalkanes on silicon. The physisorption and subsequent thermal dissociative attachment of bromoethane (EtBr), 1-bromopropane (PrBr), and 1-bromobutane (BuBr) on Si(100)-c(4×2) were examined by scanning tunneling microscopy in ultrahigh vacuum from 50 to 180 K, and interpreted by ab initio theory. These 1-bromoalkanes were found to physisorb and react exclusively over the inter-row sites of Si(100)-c(4×2), with activation barriers, E a, increasing with alkyl chain-length: E a = 343 ± 5 meV for EtBr, E a = 410 ± 6 meV for PrBr, and E a = 536 ± 2 meV for BuBr. Extensive ab initio calculations gave increasing barriers along the series: E c = 317 meV for EtBr, E c = 406 meV for PrBr, and E c = 430 meV for BuBr. On the basis of our calculated geometries, we interpret this dependence of thermal barrier on chain-length as due to the additional energy required with increasing chain-length in order to lift the alkyl chain away from the surface, in going from the initial physisorbed state to the reactive transition state. For BuBr, the measured E a significantly exceeded the calculated value. This increase in effective barrier-height could be due to a {"}dynamical delay{"} in optimizing the configuration of the alkyl chain.",

author = "Maryam Ebrahimi and Guo, {Si Yue} and Kai Huang and Tingbin Lim and McNab, {Iain R.} and Zhanyu Ning and Polanyi, {John C.} and Mark Shapero and Jody Yang",

year = "2012",

month = may,

day = "10",

doi = "10.1021/jp301773m",

language = "英语",

volume = "116",

pages = "10129--10137",

journal = "Journal of Physical Chemistry C",

issn = "1932-7447",

publisher = "American Chemical Society",

number = "18",

}

TY - JOUR

T1 - Effect of alkyl chain-length on dissociative attachment

T2 - 1-bromoalkanes on Si(100)-c(4×2)

AU - Ebrahimi, Maryam

AU - Guo, Si Yue

AU - Huang, Kai

AU - Lim, Tingbin

AU - McNab, Iain R.

AU - Ning, Zhanyu

AU - Polanyi, John C.

AU - Shapero, Mark

AU - Yang, Jody

PY - 2012/5/10

Y1 - 2012/5/10

N2 - Chemical reactivity as a function of chain-length was investigated for three 1-bromoalkanes on silicon. The physisorption and subsequent thermal dissociative attachment of bromoethane (EtBr), 1-bromopropane (PrBr), and 1-bromobutane (BuBr) on Si(100)-c(4×2) were examined by scanning tunneling microscopy in ultrahigh vacuum from 50 to 180 K, and interpreted by ab initio theory. These 1-bromoalkanes were found to physisorb and react exclusively over the inter-row sites of Si(100)-c(4×2), with activation barriers, E a, increasing with alkyl chain-length: E a = 343 ± 5 meV for EtBr, E a = 410 ± 6 meV for PrBr, and E a = 536 ± 2 meV for BuBr. Extensive ab initio calculations gave increasing barriers along the series: E c = 317 meV for EtBr, E c = 406 meV for PrBr, and E c = 430 meV for BuBr. On the basis of our calculated geometries, we interpret this dependence of thermal barrier on chain-length as due to the additional energy required with increasing chain-length in order to lift the alkyl chain away from the surface, in going from the initial physisorbed state to the reactive transition state. For BuBr, the measured E a significantly exceeded the calculated value. This increase in effective barrier-height could be due to a "dynamical delay" in optimizing the configuration of the alkyl chain.

AB - Chemical reactivity as a function of chain-length was investigated for three 1-bromoalkanes on silicon. The physisorption and subsequent thermal dissociative attachment of bromoethane (EtBr), 1-bromopropane (PrBr), and 1-bromobutane (BuBr) on Si(100)-c(4×2) were examined by scanning tunneling microscopy in ultrahigh vacuum from 50 to 180 K, and interpreted by ab initio theory. These 1-bromoalkanes were found to physisorb and react exclusively over the inter-row sites of Si(100)-c(4×2), with activation barriers, E a, increasing with alkyl chain-length: E a = 343 ± 5 meV for EtBr, E a = 410 ± 6 meV for PrBr, and E a = 536 ± 2 meV for BuBr. Extensive ab initio calculations gave increasing barriers along the series: E c = 317 meV for EtBr, E c = 406 meV for PrBr, and E c = 430 meV for BuBr. On the basis of our calculated geometries, we interpret this dependence of thermal barrier on chain-length as due to the additional energy required with increasing chain-length in order to lift the alkyl chain away from the surface, in going from the initial physisorbed state to the reactive transition state. For BuBr, the measured E a significantly exceeded the calculated value. This increase in effective barrier-height could be due to a "dynamical delay" in optimizing the configuration of the alkyl chain.

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U2 - 10.1021/jp301773m

DO - 10.1021/jp301773m

M3 - 文章

AN - SCOPUS:84861044781

SN - 1932-7447

VL - 116

SP - 10129

EP - 10137

JO - Journal of Physical Chemistry C

JF - Journal of Physical Chemistry C

IS - 18

ER -

Effect of alkyl chain-length on dissociative attachment: 1-bromoalkanes on Si(100)-c(4×2)

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