Second-order differential flame emission spectrometer

The invention provides a second-order differential flame emission spectrometer. The flame emission spectrometer changes a flame atomization temperature by regulating an oxygen gas flow of oxygen-rich air to meet the requirements of elements different in ionization energy for different atomization temperatures, and generates a characteristic spectral line with an extremely low flame background interference; and adopts the automatic scanning second-order differential precise grating monochromator technology, and can automatically subtract various background interferences near the characteristic spectral line of to-be-analyzed elements to obtain a second-order derivative spectrum. The obtained second-order derivative spectrum is converted into a frequency-modulated alternating-current signal by a photomultiplier, the frequency-modulated alternating-current signal is processed by a micro-current lock-in amplifier to obtain a direct-current analog signal having good linear relationship with the analyzed elements, the direct-current analog signal is subjected to data processing by a microprocessor to obtain a digital signal, and the digital signal is transmitted to a computer data workstation for storing, processing and printing, and realizing control on a spectrometer operating process. The invention is simple in operation, high in sensitivity and good in stability, and the detection limit of sodium ion, potassium ion, iron element and copper element is smaller than 0.1mug/L, which reaches the international leading level.