本文關(guān)鍵詞：硝酸—氨氣體系的大氣團(tuán)簇均相成核的理論研究　出處：《中國(guó)科學(xué)技術(shù)大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 硝酸銨氣溶膠 成核生長(zhǎng) 量子化學(xué) 蒸發(fā)速率

【摘要】：長(zhǎng)久以來,全球氣候發(fā)生了明顯的變化,局部或者全局區(qū)域的霧霾事件也越來越嚴(yán)重,這與大氣氣溶膠有著密不可分的關(guān)聯(lián)。氣溶膠顆粒物使得人們?nèi)藗円曇胺秶芟?交通事故頻繁發(fā)生,且對(duì)人體健康有著不可忽視的重大影響,造成心肺功能不可逆的損害。另一方面從歷史趨勢(shì)來看溫室效應(yīng)越來越嚴(yán)重,但是隨著霧霾天氣狀況的頻頻發(fā)生,溫室效應(yīng)的趨勢(shì)卻越來越平緩,這之中的原因與氣溶膠的參與有很大關(guān)聯(lián),氣溶膠由于其自身的理化性質(zhì)可以直接影響太陽(yáng)光線的凈通量,即直接影響輻射強(qiáng)迫,還可以使得云層的厚度產(chǎn)生變化和云的存在時(shí)間長(zhǎng)短來間接地改變地球-熱量系統(tǒng)的出入均衡,因此負(fù)輻射強(qiáng)迫作用可以對(duì)溫室加熱效應(yīng)有抵消作用。氣溶膠的作用可褒可貶。而了解氣溶膠的第一步是研究氣-相轉(zhuǎn)化的成核與生長(zhǎng)機(jī)制。不同類型的氣溶膠對(duì)氣候的作用效果不一樣,硫酸鹽型氣溶膠是作用效果最明顯的,具有負(fù)的輻射強(qiáng)迫的氣溶膠,但是硫排放逐漸減少,硝酸鹽氣溶膠的作用逐漸增長(zhǎng),在大氣氣溶膠組分中地位不斷上升,它也具有負(fù)的輻射強(qiáng)迫,可以抵制溫室效應(yīng)帶來的極端氣候的影響。隨著氨氣的大量排放,硝酸鹽氣溶膠大量形成,這成為霧霾狀況更加嚴(yán)重的誘因之一,從而為居民的正常生活帶來了一系列的危害。本文中通過隨機(jī)算法和人工蜂群算法來搜索構(gòu)型,然后通過量子化學(xué)程序計(jì)算結(jié)合能,初步模擬了硝酸和氨氣二元化合物由氣相單體逐漸生長(zhǎng)為超細(xì)氣溶膠團(tuán)簇的過程。計(jì)算了各個(gè)團(tuán)簇的生長(zhǎng)所需能量,以及硝酸和氨氣單體生長(zhǎng)每一步的自由能壘,為了解硝酸-氨氣體系全局穩(wěn)定性和成核生長(zhǎng)機(jī)理提供了基礎(chǔ)。具體成果如下:1.在計(jì)算方面,本論文采用隨機(jī)算法結(jié)合高斯量化程序搜索團(tuán)簇初始構(gòu)型,隨機(jī)算法在搜索分子團(tuán)簇構(gòu)型方面有很成熟的應(yīng)用。論文中選用B3LYP雜化密度泛函以及D3色散修正作用,B3LYP在描述色散作用比較薄弱,所以選用DFT-D3能夠很好的引入色散修正,對(duì)長(zhǎng)程相互作用有很好的描述�；M重疊誤差也是影響結(jié)果的一個(gè)因素之一,本論文中使用的是6-311++G(d,p)基組,考慮到大基組可以避免高估電子相關(guān)作用,能夠比較好地描述分子軌道。2.在團(tuán)簇生長(zhǎng)熱力學(xué)性質(zhì)方面計(jì)算,對(duì)硝酸和氨氣在不同化學(xué)計(jì)量比下形成的團(tuán)簇的熱力學(xué)性質(zhì)的計(jì)算結(jié)果顯示,質(zhì)子轉(zhuǎn)移以及氫鍵網(wǎng)絡(luò)在團(tuán)簇穩(wěn)定成核降低自由能的過程中尤其重要,硝酸和氨氣加入到前體團(tuán)簇中成核過程的自由能壘與硫酸-氨氣體系不同,在大氣氣溶膠生長(zhǎng)過程中沒有發(fā)揮比較明顯的作用。由生長(zhǎng)自由能反映的蒸發(fā)速率可以凸顯不同的分子單體在整體團(tuán)簇中的穩(wěn)定性,一般來說團(tuán)簇越大越穩(wěn)定,硝酸和氨氣分子數(shù)化學(xué)計(jì)量比相等可以有效降低團(tuán)簇穩(wěn)定性,除了起過渡作用的團(tuán)簇結(jié)構(gòu)會(huì)發(fā)生例外。當(dāng)團(tuán)簇分子總數(shù)相同,即m-n和n-m比較時(shí),酸的蒸發(fā)速率較氨氣低,所以團(tuán)簇的成核生長(zhǎng)取決于酸在體系中的衰減速率。
[Abstract]:For a long time, changes in global climate, local or global regional haze events are becoming more and more serious, which has a close relation with atmospheric aerosol particles. People limited the scope of vision, frequent occurrence of traffic accidents, and has a great influence to the human health, cause heart and lung the function of irreversible damage. On the other hand from the historical trend of greenhouse effect becomes more and more serious, but with the haze weather occurred frequently, the greenhouse effect of the trend is more and more gentle, is of great relevance to the cause of the aerosol and aerosol in the physical and chemical properties of its own can directly affect the net flux of the sun the light, which directly affect the radiative forcing, but also can make the cloud thickness and cloud is the length of time to indirectly change earth heat system Out of balance, so the negative radiative forcing effect can offset the effects of greenhouse heating effect. The aerosol effects of them. The first step is aerosol nucleation and growth mechanism of gas phase transformation. The effect of different types of aerosols on the climate is not the same, is the most obvious effect of sulfate aerosol the effect of aerosol radiative forcing is negative, but sulfur emissions decreased, nitrate aerosol effects gradually increasing in atmospheric aerosol component status is rising, it also has a negative radiative forcing effect can be brought against extreme climatic greenhouse. With ammonia emissions, a large number of nitrate aerosol this is one of the causes of haze formation, situation is more serious, which has brought a series of harm to the normal life of the residents. The random algorithm and artificial bee colony algorithm by this paper To search the configuration, and then through the quantum chemistry program to calculate the binding energy, the simulated process of nitrate and ammonia two compounds by gas phase monomer gradually grew into ultrafine aerosol clusters. The energy required for each cluster growth were calculated, and the nitrate and ammonia single growing every step of the free energy barrier for. To understand the global stability of nitrate and ammonia system - nucleus growth mechanism provides the basis. The main results are as follows: 1. in terms of computation, this paper adopts random algorithm with Gauss quantization procedure search cluster initial configuration, random algorithm is used to search in mature cluster configuration. Using B3LYP hybrid density functional and D3 dispersion correction the role of B3LYP in the thesis, describe the dispersion effect is relatively weak, so we choose DFT-D3 to introduce good dispersion correction, the long-range interactions are well described. Basis set superposition error is One of the factors that influence the results, used in this paper is the 6-311++G (D, P) basis set, taking into account the large groups can avoid overestimating the electron correlation effect, can better describe the thermodynamic properties of.2. molecular orbital growth in cluster calculation, calculation of the thermodynamic properties of ammonia and nitrate in different chemical cluster under the formation of the stoichiometric results showed that proton transfer and hydrogen bond network in the cluster nucleation process is especially important decrease in the free energy, nitrate and ammonia added to the nucleation process of precursor clusters in the free energy barrier and ammonia sulfuric acid system, did not play obvious role in atmospheric aerosol growth in the process of stability. Monomer in the overall cluster in different molecules by highlighting the evaporation rate of growth of free energy can reflect, in general clusters is more stable, nitrate and ammonia molecular number of stoichiometric phase Such an effect can effectively reduce cluster stability. Excepting the transition cluster structure, when the total number of clusters is the same, that is, when M-N and N-M are compared, the evaporation rate of acid is lower than that of ammonia. Therefore, the nucleation growth of clusters depends on the decay rate of acids in the system.

【學(xué)位授予單位】：中國(guó)科學(xué)技術(shù)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：X513;O648.16

【參考文獻(xiàn)】

相關(guān)期刊論文 前1條

1 王志彬;胡敏;吳志軍;岳玎利;;大氣新粒子生成機(jī)制的研究[J];化學(xué)學(xué)報(bào);2013年04期

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本文編號(hào)：1425558