Liquid State CW EPR fitting

[doliveravelarde]

Hello!
I am a graduate student, and I am working with EPR and EasySpin for the first time. I am having trouble fitting some EPR signals I acquired and I was wondering if I could have some help. I attached pictures of my signal, the description of the EPR parameters used to acquire the signal, and an image of my fitting attempt. What I need is to know the peak-to-peak of my signal and quantify the uncertainty. So, I believe what I am trying to do is to perform a least-squares fitting for peak-to-peak. I tried following the YouTube videos from the EasySpin Academy, which have been very helpful. However, since I do not know very much about EPR, and my programming skills are limited, my attempts to perform the fitting have been unsuccessful, and I am confused about how to guess the fitting parameters. Any help would be much appreciated.

Best regards,

Daniela

[thanasis]

First off: what is the frequency? The value you supply is 900 Hz. Correcting this should also correct he physically meaningless g value of 600 (should be around 2.00).

[doliveravelarde]

Thank you for your response. I am a bit unsure about what the frequency is. I have the parameters used in the pictures attached. But I see so many different frequencies that I am not sure which one should go there. I tried putting 35 for the frequency because in my parameters the Frequency Seep says 35 but MHz. However, using 35 in frequency and 600 for g, I got a fit but the g value I got was around 500. Also, about the magnetic field, I get that Exp.CenterSweep requires the center field which I got from the graph, is that right? and what about the second parameter (the width)? Which number should I put in there? Should those numbers come from the experiment description values in the pictures I included?

Here are the parameters stored:

Code: Select all

            general_version: ' 1.1'
              general_demon: ' 2.7.70'
               general_name: ' SINGLE TRACE'
            general_dconfig: ' clinepr.cfg'
            general_pconfig: ' clinepr.cfp'
           general_specmode: [1×0 char]
         general_normalized: ' false'
          general_starttime: ' Tue Dec  1 14:25:45 2020'
         general_finishtime: ' Tue Dec  1 14:25:48 2020'
          general_totaltime: ' 0h 0min 3s'
            general_tformat: ' 1'
        general_stream_axis: ' 256'
       general_no_auto_save: ' 0'
            sweep_transient: ' T,200,1,a'
               sweep_sweep0: ' P,1,1,RepTime,AFC,Field,FieldSweep,DwellTime,TimeConstant,PhaseIQ,ModAmp,RFPower,Sensitivity'
               aquisition_a: ' ;a;ChannelA'
             params_RepTime: ' 50 ms;p;PPL variable'
                 params_AFC: ' 1;p;AFC@LBAND'
               params_Field: ' -5.5 G;p;Field@LBAND'
          params_FieldSweep: ' 40 G;p;FieldSweep@LBAND'
           params_DwellTime: ' 5 ms;p;DwellTime@LBAND'
        params_TimeConstant: ' 1;p;TimeConstant@LBAND'
             params_PhaseIQ: ' 99 deg;p;PhaseIQ@LBAND'
              params_ModAmp: ' 1.8 G;p;ModAmp@LBAND'
             params_RFPower: ' -10 dBm;p;RFPower@LBAND'
         params_Sensitivity: ' 20;p;Sensitivity@LBAND'
              streams_names: ' Re'
              streams_units: [1×0 char]
          streams_dwelltime: ' 201 ms'
           streams_triggers: ' 1'
              streams_scans: ' 1'
                       prg1: 'signal a'
                       prg2: 'detect a'
           presetup_AcqMode: ' 1;AcqMode@LBAND'
            postsetup_Field: ' 0 G;Field@LBAND'
  scope_dfScopeIntWindowPos: ' 0'
scope_dfScopeIntWindowWidth: ' 100'
  scope_dfScopeBaselinePos1: ' -1'
scope_dfScopeBaselineWidth1: ' 56979424'
  scope_dfScopeBaselinePos2: ' -1'
scope_dfScopeBaselineWidth2: ' 56979648'
   scope_dfScopeBaselineOpt: ' -1'
              pack_PackAxis: ' 0'
         pack_MaxSeqPerShot: ' 0'
              warmup_WarmUp: ' 0'
         warmup_WarmUpScans: ' 0'
          warmup_WarmUpTime: ' 0 s'
               System_Shots: ' 0'
               System_XReps: ' 0'
               System_YReps: ' 0'
               System_ZReps: ' 0'
            System_Sum1Reps: ' 0'
            System_Sum2Reps: ' 0'
                   System_i: ' 0'
                   System_j: ' 0'
                   System_k: ' 0'
            System_ArmDelay: ' 10 ms'
             System_MTDelay: ' 10 ms'
                System_Wait: ' 10 ms'
                System_Time: ' 10 ms'
             PulseGen_Delay: ' 200 ms'
         PulseGen_DwellTime: ' 0 s'
        PulseGen_StartDelay: ' 0 s'
       PulseGen_No_Responce: ' Never'
             PulseGen_Crash: ' Never'
           PulseGen_Failure: ' Never'
              LBAND_AcqMode: ' FieldSweep'
              LBAND_PhaseRF: ' 55 deg'
              LBAND_PhaseIQ: ' 99 deg'
                LBAND_Field: ' 0 G'
           LBAND_FieldSweep: ' 40 G'
            LBAND_Frequency: ' 660 kHz'
            LBAND_FreqSweep: ' 35 MHz'
              LBAND_RFPower: ' -10 dBm'
                  LBAND_AFC: ' On'
              LBAND_ModFreq: ' 20 kHz'
               LBAND_ModAmp: ' 1.8 G'
            LBAND_DwellTime: ' 5 ms'
         LBAND_TimeConstant: ' 5 ms'
          LBAND_Sensitivity: ' 10 mV'
                LBAND_TuneV: ' 0 V'
              GRAD_TrigMode: ' Normal'
        GRAD_AOsettlingTime: ' 0 s'
           GRAD_AIfrequency: ' 1 kHz'
                 GRAD_GradX: ' 0 G/cm'
                 GRAD_GradY: ' 0 G/cm'
                 GRAD_GradZ: ' 0 G/cm'
                   GRAD_TMP: ' 0 V'
           aliases_ChannelA: ' 0.3552'
              aliases_Field: ' 0 G'
        sample_info_project: [1×0 char]
        sample_info_mouseID: [1×0 char]
     sample_info_experiment: [1×0 char]
    sample_info_sample_info: ' **T**'
  sample_info_sample_info_0: ' *****'
              sample_info_Q: ' 0'
      sample_info_resonator: [1×0 char]
       sample_info_power_dB: ' 0'
         exp_info_file_type: [1×0 char]
             exp_info_type1: [1×0 char]
       exp_info_calibration: ' 0'
          exp_info_template: [1×0 char]
                     xlabel: 'a, s'

Thank you once again!

[thanasis]

You can derive the frequency by the magnetic field. I cannot make out the format of the parameters very well. It seems that the center field is -5.5 G?

Anyway, you can use the resonance conditions ΔE = mS * g * B * μB to derive the energy, hence frequency.

[doliveravelarde]

Oh, I see. Thank you!