表面单层组装多环芳烃荧光行为的Monte Carlo模拟(Ⅱ)——柔性连接臂长度效应  

Monte Carlo simulation of the fluorescence behavior of an aromatic compound assembled on a substrate surface(Ⅱ)

作　　者：王渭娜[1] 房喻[1] 张政朴[2] 姜心田[1] 

机构地区：[1]陕西师范大学化学与材料科学学院,陕西西安710062 [2]南开大学吸附分离材料国家重点实验室,天津300071

出　　处：《计算机与应用化学》2004年第4期533-537,共5页Computers and Applied Chemistry

基　　金：国家自然科学基金(20173035;29973024);陕西省自然科学基金(2002B11)

摘　　要：用 Monte Carlo 方法模拟了惰性基片表面单层组装多环芳烃(传感元素)的荧光行为。考察了在不同长度的柔性连接臂情况下,基片表面传感元素固定化百分率、传感元素激发百分率(光吸收效率)以及传感元素分子在介质中相互缔合形成激基缔合物趋势大小(用 P 表示,P 值介于0～1之间)等因素对传感元素激基缔合物荧光发射强度与单体荧光发射强度(I_E/I_M)之比所产生的影响。结果表明,传感元素特性参数 P 的大小对薄膜传感特性影响相对较小。在不考虑量子产率的前提下,就惰性基片而言,要将 I_E/I_M控制在0.5～2之间,连接臂的长度至少可在3～12之间调节,传感元素固定化百分率可控制在30%～70%之间。此外,传感元素的激发百分率也对薄膜的 I_E/I_M 产生显著影响。一般而言,低的激发百分率对应于较高的 I_E/I_M比值,但过低的激发百分率也伴随着弱的荧光发射。因此,要使传感薄膜发挥最好的传感特性,激发百分率也不可以太小。Assembly of molecules on thin films to form highly ordered architectures is one of the important approaches to prepare func-tional films.In addition to other advantages,chemical sensors in film state are much easier to be made into devices.Thus,a series ofsensing films based upon the supra-molecular behavior of aromatic compounds immobilized on substrate surfaces and its dependence tothe composition of the medium have been successfully prepared in our laboratory during the last few years.In the present study,the flu-orescence behavior of a functional plate,of which the surface is functionalized by immobilization of a single layer aromatic compound(sensing element),is simulated by Monte Carlo method.For the systems of various spacer lengths,the effects of the immobilizationdensity of a sensing element,the excitation efficiency(the absorption efficiency),and the association efficiency(P,which should begreater than 0 and lower than 1)between the molecules of the sensing element on the ratio of the excimer emission to the monomer e-mission of the plate have been systematically examined.It was demonstrated that the characteristic parameter P of a given sensing ele-ment has limited effect upon the film's I_E/I_M ratios,for a sensing film of spacer length of 3～12,a I_E/I_M value between 0.5～2 may beobtained only when the density of the sensing element immobilized on the inert substrate is controlled between 30～70%.It is to benoted that lower photon excitation efficiency corresponds to a greater I_E/I_M values.But,too low excitation efficiency means weaker fluo-rescence,resulting in difficult in measurement,thereby,excitation efficiency should not be too low.

关 键 词：MONTE CARLO模拟 传感元素 多环芳烃 荧光 激基缔合物 

分 类 号：O644[理学—物理化学]