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帮我翻译下 In this work,the direct photoreduction process of the AgNO3-NaCit solutions was carried out without the previous addition of silver seeds.Besides,we studied the wavelength influence on the synthesis of Ag nanoparticles.Finally,we used these nanoparticles as SERS colloids.SERS is of great interest because it constitutes an important tool for the high-sensitivity detection of a broad kind of compounds.For thispurpose,pyridine andcaffeine were used as test molecules.Pyridine (C5H5N) is an intermediate in the synthesis of insecticides,herbicides,pharmaceuticals,etc.On the other hand,caffeine (C8H10N4O2) is used as a central nervous system stimulant,having the effect of temporarily warding off drowsiness and restoring alertness.ExperimentalMaterialsAll reagents were analytical grade,purchased from Sigma andMerck and used without further purification.Pyridine,99.9%; caffeine,99%; AgNO3,99.9999%; and sodium citrate,99% wereused in this work.Aqueous solutions were prepared using tridistilled water.Pyridine and caffeine aqueous solutions with aconcentration of 2000 ppm were used for SERS tests.Synthesis of Ag nanoparticlesIn a typical synthesis,42.5 mg of AgNO3 and 73.5 mg of sodiumcitrate (NaCit) were dissolved in 250 ml of tri-distilled water at room temperature.This solution was separated in 15 aliquots,the first was used as reference and the other 14were exposed towhite light (conventional fluorescent tube,Sanalec 26W,Coolwhite; 350 nm < λ < 700 nm) from 1–24 h.The same procedure was carried out in order to explore the colloid behavior at different wavelengths; colored glass filters in the blue 350 < λ < 482 nm; cyan 370 < λ < 563 nm; green 396 < λ < 600 nm; and orange 563 < λ < 700 nmwere interposed between the fluorescent tube and the samples.On the other hand,a UV lamp (λ = 365 nm) was used as another light source to evaluate the reduction process.InstrumentationRaman spectra were recorded with a Raman dispersive spectrometer,model Almega XR.Macro compartment was used both for focusing the laser on the liquid samples and for collecting the scattered light in a 180
帮我翻译下 In this work,the direct photoreduction process of the AgNO3-NaCit solutions was carried out without the previous addition of silver seeds.Besides,we studied the wavelength influence on the synthesis of Ag nanoparticles.Finally,we used these nanoparticles as SERS colloids.SERS is of great interest because it constitutes an important tool for the high-sensitivity detection of a broad kind of compounds.For thispurpose,pyridine andcaffeine were used as test molecules.Pyridine (C5H5N) is an intermediate in the synthesis of insecticides,herbicides,pharmaceuticals,etc.On the other hand,caffeine (C8H10N4O2) is used as a central nervous system stimulant,having the effect of temporarily warding off drowsiness and restoring alertness.ExperimentalMaterialsAll reagents were analytical grade,purchased from Sigma andMerck and used without further purification.Pyridine,99.9%; caffeine,99%; AgNO3,99.9999%; and sodium citrate,99% wereused in this work.Aqueous solutions were prepared using tridistilled water.Pyridine and caffeine aqueous solutions with aconcentration of 2000 ppm were used for SERS tests.Synthesis of Ag nanoparticlesIn a typical synthesis,42.5 mg of AgNO3 and 73.5 mg of sodiumcitrate (NaCit) were dissolved in 250 ml of tri-distilled water at room temperature.This solution was separated in 15 aliquots,the first was used as reference and the other 14were exposed towhite light (conventional fluorescent tube,Sanalec 26W,Coolwhite; 350 nm < λ < 700 nm) from 1–24 h.The same procedure was carried out in order to explore the colloid behavior at different wavelengths; colored glass filters in the blue 350 < λ < 482 nm; cyan 370 < λ < 563 nm; green 396 < λ < 600 nm; and orange 563 < λ < 700 nmwere interposed between the fluorescent tube and the samples.On the other hand,a UV lamp (λ = 365 nm) was used as another light source to evaluate the reduction process.InstrumentationRaman spectra were recorded with a Raman dispersive spectrometer,model Almega XR.Macro compartment was used both for focusing the laser on the liquid samples and for collecting the scattered light in a 180
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