氧气常压介质阻挡放电的发射光谱及能量传递机理

Emission Spectroscopy and Energy Transfer Process in Atmospheric Dielectric Barrier Discharge in Oxygen

为研究氧气常压介质阻挡放电中的物理化学行为,以纯氧作为放电体系,用发射光谱(optical emission spectroscopy)诊断技术分析了等离子体中可能存在的化学活性物种.利用在500-950nm范围的氧原子发射光谱计算出等离子体中的电子温度为(1.02±0.03)eV;观测了760nm处的具有清晰转动结构的氧气A带(atmospheric band)O2(b1Σg+-X3Σg-),并用其转动结构计算了转动温度(气体温度)为(650±20)K;在500-700nm范围观测了氧气的第一负带系(firstnegativesystem)O+2(b4Σ-g-a4Πu),在190-240nm范围观测了微弱但特征清晰的氧气的Hopfield带系O2+(c4Σu+-b4Σg-).研究发现,在氧气常压介质阻挡放电等离子体中存在多种激发态氧原子、激发态氧气分子、基态和激发态氧气分子离子等反应活性物种,这些活性物种的形成涉及氧气分子的激发、解离和电离等多种过程,每个过程都包含多个能量传递步骤,氧分子解离产生的氧原子是导致一系列高激发态氧原子生成和氧气电离激发的主要因素.

To investigate physical chemical behaviors of dielectric barrier discharge at atmospheric pressure in oxygen, the chemical active species which might exist in plasma were analyzed with the diagnosis technique of optical emission spectroscopy （OES） in oxygen discharge system. From the oxygen atom emission spectra in 500-950 nm, the electronic temperature was calculated by some atomic lines to be （1.02±0.03） eV. The oxygen atmospheric band O2 （b1Σ＋g-X3Σ-g） in 760 nm was analyzed, and the rotational temperature （gas temperature） was calculated by its rotational structure to be （650±20） K. The first negative system O＋2（b4Σ-g-a4Πu） in 500-700 nm and the Hopfield system O＋2（c4Σ＋u-b4Σ-g） in 190-240 nm were observed. The research showed that there were various reactive species in plasma of dielectric barrier discharge at atmospheric pressure in oxygen, such as a series excited oxygen atoms, excited oxygen molecules, ground and excited states of oxygen molecular ions. The formation of reactive species concerned many procedures of excitation, dissociation and ionization of oxygen, many energy transfer steps were included in every procedure. The oxygen atoms produced from oxygen molecule dissociation were ruling factor leading to generate reactive species besides electron.