Preparation Of High Concentration NV Centers In Diamond And Weak Magnetic Detection

The Nitrogen-Vacancy center(NV center)in diamond has great optical property and special energy level structure.The spin state of NV center can be regulated by laser and microwave.Also,it has a long spin coherence time at room temperature.It has been widely used in the field of quantum information and quantum sensing.At present,the use of NV color centers for quantum detection mainly includes two forms:single NV center detection and ensemble NV center detection.Because the ensemble NV center detection has a higher signal-to-noise ratio,this thesis focuses on the ensemble NV center for weak magnetic detection.This thesis mainly studies how to prepare high-concentration NV centers in diamond,including using various methods such as electron irradiation and annealing.This paper explores how to use the NV color center to detect weak magnetic fields,including using electron microscope,confocal microscopy,software simulation and other methods to study the magnetic field distribution of nano-magnetic particles.Finally,the steady-state fluorescence spectroscopy,time-resolved fluorescence spectroscopy,and pump-probe techniques were used to study the solvent effects and excited state kinetics of a thiophene multibranched structure in different solvents.The main contents of this thesis are as follows:1.The diamond samples were conducted with different electron irradiation doses and different annealing temperatures to investigate the effects of electron irradiation doses and annealing temperatures on the generation of NV color center concentration.The diamond samples were then subjected to fluorescence spectrum under the same conditions,and the optimal electron irradiation dose and annealing temperature were obtained by comparing the fluorescence intensity after each experiment.Through processing and testing,we found that the highest NV color center concentration can be obtained at an electron irradiation dose of 1×10~188 e~-/cm~2 and an annealing temperature of about 900?.2.The nano-magnetic particles were dispersed and obeserved by spin coating and electron microscope.Then,the laser source was used through confocal microscopy device to initialize the NV color center,and the microwave was used to manipulate the spin state of the NV color center.The magnetic field distribution of a single nanomagnetic particle was measured using the NV color center as a probe.3.Three newly synthesized multi-branched alkyl-triphenylamine end-capped triazines,ATT-(1-3)have been characterized in different solvents by steady-state and time-resolved spectrum.The positions of the emission peaks and absorption peaks of each sample in the solvent were studied using steady-state spectroscopy.The time-resolved spectroscopy and pump-probe techniques were used to study the excited state dynamics of the samples.By comprehensively analyzing the results of various characterization methods,we find that due to the solvent effect,the kinetic process of the excited state of the sample accelerates with the increase of the polarity of the solvent.In addition,the dynamics of the excited state of the sample also accelerated with the increase of the donor branch number of samples.