CN102583267A - Method for preparing electron spin resonance standard substance by using hydrothermal method - Google Patents

Abstract

The invention discloses a method for preparing an electron spin resonance standard substance by using a hydrothermal method. The method comprises the following steps of: putting a tellurium compound, a reducing agent and a surfactant into a polytetrafluoroethylene reaction kettle; adding deionized water to the polytetrafluoroethylene reaction kettle; uniformly stirring and mixing the mixture; reacting the mixture under a sealed condition for 110-180 minutes at 135-145 DEG C; after finishing the reaction, cooling an obtained reactant to room temperature; and centrifuging, washing and drying the cooled reactant in sequence to obtain the electron spin resonance standard substance. Because a corresponding value g in an electron spin resonance spectroscopy of the standard substance prepared by using the method disclosed by the invention is definite, the value g can be used for calibrating the value g of an unknown substance; in addition, tellurium nanocrystalline prepared by using the method contains fixed free radical concentration; through the two characteristics, the standard substance prepared by using the synthetic technique can be used for quantitatively analyzing the electron spin resonance.

Description

A kind of method of Hydrothermal Preparation ESR spectrum standard substance

One, technical field

The present invention relates to a kind of preparation method of ESR spectrum quantitative analysis standard substance, specifically a kind of method of Hydrothermal Preparation ESR spectrum standard substance.

Two, background technology

ESR spectrum is one of research electron spinning energy level transition the most directly means, also is to detect the effective means of radical.Common electronic self-rotary resonant technology relates to the measurement of two physical quantitys: first g-factor, and it is a physical quantity relevant with radical structure, is the coupled reflection between unpaired electron spin angular momentum and the orbital momentum in essence; It two is the concentration of radical, representes that with the spin population that is contained in every gram, the every milligram of sample it is proportional to the area of the electron spin resonance signal absorption peak of this sample.Usually the measurement of g value need utilize the g value of known standard thing to demarcate, and in addition, the absolute measurement that do number of free radical is very difficult; The general relative method that adopts; Signal through with standard substance and unknown sample carries out integration, and relatively, can calculate the spin concentration of unknown sample radical.The ESR spectrum standard substance that generally adopts at present is main silicon carbide, and the problem that this standard substance mainly exists is that production cost is high, and output is few, so price is very expensive.

Three, summary of the invention

The present invention aims to provide the method that a kind of preparation cheaply is used as the ESR spectrum standard substance, and technical problem to be solved is to select a kind of material can substitute existing ESR spectrum standard substance silicon carbide.

The material that the present invention selects is the nanocrystalline alternative existing ESR spectrum standard substance of tellurium.

Technical solution problem of the present invention adopts following technical scheme:

The method of Hydrothermal Preparation ESR spectrum standard substance of the present invention is characterized in that operating according to the following steps:

Compound 0.4-0.5g, reductive agent 0.7-0.8g and the tensio-active agent 0.3-0.5g of tellurium are placed the tetrafluoroethylene reaction kettle; Add the 30-50mL deionized water; Mix; In 135-145 ℃ of reaction 110-180 minute, reduce to room temperature after reaction finishes in confined conditions, it is nanocrystalline after centrifugal, washing and drying, to obtain ESR spectrum standard substance tellurium successively;

Said washing is successively through ethanol, acetone and deionized water wash;

The compound of said tellurium is selected from the Na of purity>=99.99% ₂TeO ₃, K ₂TeO ₃, H ₂TeO ₃Or TeO ₂

Said reductive agent is selected from the Na of purity>=99.9% ₂S ₂O ₃, Na ₂SO ₃, thiocarbamide, urea or Hydrazine Hydrate 80;

Said tensio-active agent is selected from Vinylpyrrolidone polymer, Z 150PH or the cetyl trimethylammonium bromide of purity >=99.9%.

Said alcoholic acid mass percentage concentration is 99.9%, and the mass percentage concentration of said acetone is 99.5%.

Theoretical basis of the present invention is: on the one hand; In the aqueous solution; The process of growth of tellurium nanocrystals receives the not high influence of crystallization temperature; Can be in a large amount of tellurium atom room (being defective) of the inner introducing of nanocrystal, these defectives are equal to radical, can come out through the electron spin resonance spectroscopy measurement.Because the completely specified structure of this defective, the g value that this radical is corresponding is changeless, and therefore, it can be used for the demarcation of electronic self-rotary resonant technology g value.On the other hand, the concentration of these radicals is decided by the synthetic temperature, thereby can be nanocrystalline through selecting suitable temperature to prepare the tellurium with specific number of free radical.In addition, under the growing environment of solvent, because reaction conditions is gentle, prepared nanocrystallinely be not easy oxidizedly, and the nanocrystalline output of this method synthetic tellurium is big, and cost is low, and therefore, institute's synthetic product can be as the standard substance of ESR spectrum.

Compared with present technology, beneficial effect of the present invention is embodied in:

1, the present invention is based on solution reaction easily in the inner characteristics of introducing a large amount of defectives of nanostructure.Because the structure of this defective is specific, thereby corresponding g value is also confirmed in its electron spin resonance spectroscopy, therefore, it can be used as unknown material g value demarcation.In addition, the nanocrystalline fixed number of free radical that contains of tellurium of this method preparation.The standard substance that these two characteristics orders use this synthetic technology preparation can be used for the quantitative analysis of ESR spectrum.

2, the standard substance of traditional ESR spectrum is the silicon carbide that the method through pyritous obtains, and cost is higher, and output is lower.The present invention has adopted hydrothermal method, one-step synthesis, and technology is simple, is fit to mass preparation, can solve the problem that present ESR spectrum standard substance exists;

3, owing to ESR spectrum standard substance commonly used costs an arm and a leg; Therefore present most ESR spectrometer is not equipped with this standard substance; Therefore do not possess the ability of carrying out quantitative analysis, this has limited the application of electron spin resonance spectroscopy greatly, and the present invention will thoroughly change this present situation; Its application will make the quantitative analysis of ESR spectrum become generally, promote the development of this field correlative study.

Four, description of drawings

Fig. 1 is the x-ray diffraction pattern (Rigaku D/Mar-rB) of the nanocrystalline ESR spectrum standard substance of tellurium of the present invention's preparation.Through with the comparative analysis of JCPDS card, obtain the nanocrystalline thing of tellurium and be mutually the plumbous zinc ore structure of hexagonal.

Fig. 2 is the sem (Philip XL30-FEG) of the nanocrystalline ESR spectrum standard substance of tellurium of the present invention's preparation.The nanocrystalline diameter of tellurium is about 600～900nm among the figure.

Fig. 3 is the transmission electron microscope photo of the nanocrystalline ESR spectrum standard substance of tellurium of the present invention's preparation, and lower right corner illustration is SEAD (JEOL JEM-2010).Can see that from figure the tellurium nanocrystal surface is smooth clean, crystallinity is relatively good.SEAD surface tellurium is nanocrystalline to be nearly hexagonal symplex structure.

Fig. 4 is the electron spin resonance spectroscopy figure of the nanocrystalline ESR spectrum standard substance of tellurium of the present invention's preparation and the contrast (JEOL JEM-2010) of silicon carbide.1 is the nanocrystalline curve of tellurium among the figure, the 2nd, and the curve of silicon carbide, * 5 expression curves 2 longitudinal axis data multiply by 5 times, so that observe contrast.Curve can calculate the integral area A silicon carbide of nanocrystalline integral area ATe of tellurium and silicon carbide.

Five, embodiment

Embodiment 1:

1, taking by weighing 0.5g purity is 99.99% Na ₂TeO ₃, 0.8g purity is 99.9% Na ₂S ₂O ₃With 0.3g purity be 99.9% Vinylpyrrolidone polymer, the capacity of putting into is the tetrafluoroethylene reaction kettle of 50ml;

2, in reaction kettle, add the 40mL deionized water, magnetic agitation was mixed to evenly in 30 minutes, and the sealing polytetrafluoroethyllining lining is put into automated temperature control oven, and through 30 minutes, oven temperature rose to 140 ℃, kept this thermotonus 120 minutes;

3, reaction is reduced to room temperature after finishing; Spinning obtains grey matter; Use 99.9wt% ethanol, 99.5wt% acetone and deionized water wash successively, with being placed on the vacuum drying oven inner drying, finally obtaining gray product, to be prepared ESR spectrum standard substance tellurium nanocrystalline.

Embodiment 2:

1, taking by weighing 0.2g purity is 99.99% H ₂TeO ₃, 0.5g purity is 99.9% Na ₂S ₂O ₃With 0.4g purity be 99.9% Vinylpyrrolidone polymer, the capacity of putting into is the tetrafluoroethylene reaction kettle of 50ml;

2, in reaction kettle, add the 40mL deionized water, magnetic agitation was mixed to evenly in 30 minutes, and the sealing polytetrafluoroethyllining lining is put into automated temperature control oven, and through 30 minutes, oven temperature rose to 120 ℃, kept this thermotonus 120 minutes;

3, reaction is reduced to room temperature after finishing; Spinning obtains grey matter; Use 99.9wt% ethanol, 99.5wt% acetone and deionized water wash successively, with being placed on the vacuum drying oven inner drying, finally obtaining gray product, to be prepared ESR spectrum standard substance tellurium nanocrystalline.

Embodiment 3:

1, taking by weighing 0.45g purity is 99.99% K ₂TeO ₃, 0.75g purity is that 99.9% Hydrazine Hydrate 80 and 0.35g purity are 99.9% Z 150PH, the capacity of putting into is the tetrafluoroethylene reaction kettle of 50ml;

2, in reaction kettle, add the 40mL deionized water, magnetic agitation was mixed to evenly in 30 minutes, and the sealing polytetrafluoroethyllining lining is put into automated temperature control oven, and through 30 minutes, oven temperature rose to 180 ℃, kept this thermotonus 120 minutes;

3, reaction is reduced to room temperature after finishing; Spinning obtains grey matter; Use 99.9wt% ethanol, 99.5wt% acetone and deionized water wash successively, with being placed on the vacuum drying oven inner drying, finally obtaining gray product, to be prepared ESR spectrum standard substance tellurium nanocrystalline.

Through the experiment contrast of embodiment 1-3, on the one hand, no matter how condition changes, because the defect kind of being introduced is consistent all the time, so consistent being maintained about 2.005 of g value of standard substance.On the other hand, through the height of control reaction temperature, can reach the spin concentration of adjustment criteria thing, when the temperature of hydro-thermal reaction is higher than 160 ℃, the spin concentration of standard substance is lower than 2 * 10 ¹³Mg ^-1, when temperature was between 140-160 ℃, the spin concentration value was between 2 * 10 ¹³-5 * 10 ¹³Mg ^-1, to be about be 1 * 10 to the spin concentration value when temperature is lower than 140 ℃ ¹⁴Mg ^-1We have tested the g value and the spin concentration size of the standard substance of this method preparation also to the product utilization electronic self-rotary resonant technology in addition, and contrast with silicon carbide.As shown in Figure 4.

Embodiment 4:

1, take by weighing the tellurium manocrystalline powders of 30mg the present invention preparation, putting into diameter is 0.5mm, puts into the vacuum drying oven thorough drying after the silica tube bottom of one section sealing and the compacting.

2, take out silica tube from vacuum drying oven, putting into model is Bruker EMX-10/12 ESR spectrum regulator.

3, ESR spectrum regulator parameter is set, under the 9.75GHz operating frequency, the microwave modulating frequency is 0.2GHz simultaneously, has 3440 Gausses slowly to be elevated to 3540 Gausses in magnetic field, and energy maintains 20mW.Can obtain Fig. 4 numeral curve of 1 of getting the bid.To take by weighing thing and be changed to silicon carbide, the constant Fig. 4 of obtaining of all the other test conditions numeral curve of 2 of getting the bid.

4, according to the content of being mentioned in the background technology, the nanocrystalline g value of synthetic tellurium confirms that resulting Fig. 4 promptly is the collection of illustrative plates of the nanocrystalline a kind of standard of tellurium, the nanocrystalline electron spinning concentration C of synthetic tellurium when the temperature of hydro-thermal reaction is 140 ℃ _Sp:TeBe 2.7 * 10 ¹³Mg ^-1, utilize ESR spectrum regulator integral and calculating analysis software to calculate the integral area A of curve _TeBe 4973a.u..The electron spinning concentration C of silicon carbide _{Sp: silicon carbide}Be 0.56 * 10 ¹³Mg ^-1, the integral area A of silicon carbide _{Silicon carbide}Be 1037a.u..

To take by weighing thing and be changed to the Si manocrystalline powders, obtain ESR spectrum ability spectrogram, from figure, calculate integral area A _SiBe 2349a.u..Through formula C _Sp:Si=(A _Si÷ A _Te) * C _Sp:TeObtain the nanocrystalline electron spinning concentration C of Si _Sp:SiBe 1.273 * 10 ¹³Mg ^-1Through silicon carbide C _Sp:Si=(A _Si÷ A _{Silicon carbide}) * C _{Sp: silicon carbide}Obtain the nanocrystalline electron spinning concentration C of Si _Sp:SiBe 1.269 * 10 ¹³Mg ^-1Can know from data, with tellurium nanocrystalline do the measured data of ESR spectrum standard substance and silicon carbide very approaching, the standard substance of the present invention preparation possesses the ability of carrying out quantitative analysis.

Claims (2)

1. the method for a Hydrothermal Preparation ESR spectrum standard substance is characterized in that operating according to the following steps:

Compound 0.4-0.5g, reductive agent 0.7-0.8g and the tensio-active agent 0.3-0.5g of tellurium are placed the tetrafluoroethylene reaction kettle; Add the 30-50mL deionized water; Mix; In 135-145 ℃ of reaction 110-180 minute, reduce to room temperature after reaction finishes in confined conditions, after centrifugal, washing and drying, obtain the ESR spectrum standard substance successively;

Said washing is successively through ethanol, acetone and deionized water wash;

The compound of said tellurium is selected from the Na of purity>=99.99% ₂TeO ₃, K ₂TeO ₃, H ₂TeO ₃Or TeO ₂

Said reductive agent is selected from the Na of purity>=99.9% ₂S ₂O ₃, Na ₂SO ₃, thiocarbamide, urea or Hydrazine Hydrate 80;

Said tensio-active agent is selected from Vinylpyrrolidone polymer, Z 150PH or the cetyl trimethylammonium bromide of purity >=99.9%.

2. preparation method according to claim 1 is characterized in that: said alcoholic acid mass percentage concentration is 99.9%, and the mass percentage concentration of said acetone is 99.5%.

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