本文關鍵詞：惰性氣體原子以及雙原子分子在飛秒強激光場中的里德堡態(tài)激發(fā)　出處：《吉林大學》2015年博士論文　論文類型：學位論文

  更多相關文章： 里德堡態(tài)激發(fā) 強激光場 原子和雙原子分子 受挫的隧穿電離

【摘要】：隨著現(xiàn)代科技的發(fā)展，超快激光與原子分子相互作用產生了許多新的強場物理過程，如高次諧波發(fā)射，閾上電離和非序列雙電離等。其中強場下的中性里德堡態(tài)激發(fā)作為一個新的強場物理現(xiàn)象，不僅被認為是三步重散射模型的重要補充，而且是中性粒子有效加速的一種可能手段，近年來受到了大量理論和實驗工作者的關注。 盡管從2008年開始至今已有許多關于強場中里德堡態(tài)激發(fā)的研究被發(fā)表，仍然存在一些問題亟待進一步的深入研究予以解決。例如，強場中原子里德堡態(tài)激發(fā)的物理機制；里德堡態(tài)激發(fā)與其他強場物理過程的競爭關系；中性分子的里德堡態(tài)激發(fā)；各種激光參數(shù)（如激光波長，橢偏率，光強）的影響，以及原子和分子的里德堡態(tài)激發(fā)過程對比等。 本論文中，我們使用脈沖電場電離里德堡態(tài)的方法結合飛行時間質譜，研究了不同原子和分子的里德堡態(tài)激發(fā)現(xiàn)象。通過測量強場電離和里德堡態(tài)激發(fā)的幾率隨激光參數(shù)（光強和橢偏率）的變化關系，，并比較原子的里德堡態(tài)激發(fā)和非序列雙電離，相同電離限的原子和分子的里德堡態(tài)激發(fā)過程，以及紅外和紫外激光場下里德堡態(tài)激發(fā)過程的區(qū)別，討論了原子和分子在紅外和紫外激光場下的里德堡態(tài)激發(fā)機制，分析了里德堡態(tài)激發(fā)與其他強場物理過程的競爭關系。獲得了以下主要的研究結果： 1）測量了惰性氣體原子（He，Ar，Xe）在800nm飛秒激光場中里德堡態(tài)激發(fā)的產量，及其隨激光參數(shù)（光強，橢偏率）的變化關系，同時作為比較，實驗中也測量了原子的非序列雙電離過程。研究發(fā)現(xiàn)，里德堡態(tài)激發(fā)和非序列雙電離呈現(xiàn)相似的現(xiàn)象，如隨著原子序數(shù)的增加，其產率都增加，橢偏率依賴的程度隨之減��；相比于非序列雙電離，所有原子的里德堡態(tài)激發(fā)的產率較大，對激光橢偏率的依賴更弱。結合已有的研究報道和相關理論，我們分析并討論了800nm強激光場中原子里德堡態(tài)激發(fā)的內在物理機制，即受挫的隧穿電離機制。 2）首次在實驗上觀測到分子在飛秒激光場下的里德堡態(tài)激發(fā)現(xiàn)象。對比研究了雙原子分子N2和O2與其同伴原子Ar和Xe里德堡態(tài)激發(fā)幾率。研究發(fā)現(xiàn)，與強場電離類似，N2分子表現(xiàn)為與原子Ar類似的里德堡態(tài)激發(fā)幾率，而與原子Xe相比，O2分子的里德堡態(tài)激發(fā)幾率明顯被抑制，且里德堡態(tài)激發(fā)的抑制比強場電離抑制更為明顯。量子計算定性的重現(xiàn)了實驗結果。分析表明，不同分子的軌道結構導致的出射電子角分布的不同是決定里德堡態(tài)激發(fā)幾率的重要因素。 3）研究了紅外和紫外飛秒激光中NO的里德堡態(tài)激發(fā)現(xiàn)象。首次觀測到了紫外飛秒強激光場中的里德堡態(tài)激發(fā)現(xiàn)象。實驗發(fā)現(xiàn)NO*在800nm和400nm波長下對激光橢偏率的依賴不同，結合之前的實驗結果和理論模型，認為NO分子在紫外光場中的里德堡態(tài)激發(fā)機制為多光子共振激發(fā)過程。
[Abstract]:With the development of modern technology, the interaction of ultrafast laser with atoms and molecules to produce many new high field physics process, such as harmonic emission, threshold ionization and non sequential double ionization. The neutral Rydberg states of strong field excitation as a new high field physics phenomenon, not only is considered to be an important supplement of the three step heavy scattering model, and is a possible means of neutral particles effectively accelerated, in recent years has been a large number of theoretical and experimental researchers.
Although from the beginning of 2008 has been many studies on excited Rydberg states in the strong field was published, there are still some problems need to be solved further study. For example, the physical mechanism of atomic Rydberg states excitation magnetic field; Rydberg state excitation competitive relationship with other strong field physics; Rydberg states of neutral molecules excited; various laser parameters (such as laser wavelength, ellipticity, intensity) effect, and Rydberg states of atoms and molecules of the excitation process of contrast.
In this paper, we use the method of pulsed field ionization of Rydberg states with time-of-flight mass spectrometry, studied the phenomenon of different excitation Rydberg states of atoms and molecules. The probability of measuring strong field ionization and excitation of Rydberg states with laser parameters (intensity and ellipticity) changes, and compare the Rydberg atom and non excitation sequential double ionization of Rydberg atoms and molecules, the same ionization limit the excitation process, and the difference between Rydberg states of infrared and ultraviolet laser field excitation, excitation mechanism of atoms and molecules in the infrared and ultraviolet laser field of the Rydberg States discussed the Rydberg state excitation in competition with other strong field physics. Analysis obtained the following main results:
1) inert gas atoms (He, Ar, Xe measurement) excited Rydberg states in 800nm femtosecond laser field in production, and with the laser parameters (intensity, ellipticity) changes, at the same time as the comparison experiment also measured in non sequential double ionization process of atoms. The study found the Rydberg states the excitation and non sequential double ionization showed similar phenomena, such as the atomic number increases, the yield increased, the ellipticity dependence decreases; compared to the non sequential double ionization of Rydberg states of all atoms excited by the yield greater dependence on laser ellipticity is weaker. Combined with the existing research reports and the related theory, we analyzed and discussed the intrinsic physical mechanism of excited atomic Rydberg states of 800nm in strong laser field, which frustrated the tunneling ionization mechanism.
2) the first observation of the Rydberg molecules in femtosecond laser field in the experiment. A comparative study of the phenomena of excitation of diatomic molecules N2 and O2 and its companion Ar and Xe atomic Rydberg states excitation probability. The study found that similar strong field ionization, N2 molecule is similar to Fort Reed state of atom Ar excitation probability. Compared with the Xe atom, Rydberg O2 molecule excitation probability was obviously inhibited, and the inhibition of the Rydberg state excitation inhibition was more obvious than the strong field ionization. Quantum computation qualitatively reproduce the experimental results. The analysis shows that different track structures lead to different molecular electron angular distribution is an important factor in determining Rydberg States excitation probability.
3) on the phenomenon of the Rydberg state excitation infrared and ultraviolet femtosecond laser in NO. The first observation of the Rydberg state UV intense femtosecond laser field excitation phenomenon. The experimental results showed that NO* dependent bias rate of laser elliptical in 800nm and 400nm wavelength under different experimental results and combined with the previous theoretical model, think the Rydberg NO molecule in the UV field excitation mechanism for multiphoton resonance excitation process.

【學位授予單位】：吉林大學
【學位級別】：博士
【學位授予年份】：2015
【分類號】：O562

【參考文獻】

相關期刊論文 前1條

1 余本海;李盈儐;李方濤;;Microscopic Dynamics of Nonsequential Double Ionization by Elliptically Polarized Few-Cycle Laser Pulses[J];Communications in Theoretical Physics;2013年06期

本文編號：1363398