Absorption Of Rubidium Research Articles

Verifying thermodynamic equilibrium of molecular manifolds: Kennard-Stepanov spectroscopy of a molecular gas

The degree of thermalization of electronically excited state manifolds of an absorber can be tested via optical spectroscopy. In the thermalized-manifold case, the ratio of absorption and emission is expected to follow a universal Boltzmann-type frequency scaling, known as the Kennard-Stepanov relation. Here, we investigate absorption and emission spectral profiles of rubidium, cesium, and potassium molecular dimers in a high-pressure argon buffer-gas environment and study the effect of collisionally induced redistribution. We find that, despite the use of nonlinear excitation techniques, the ratio of absorption and emission well follows the Kennard-Stepanov scaling for a variety of molecular transitions. We conclude that the upper electronic state rovibrational manifold of the molecular gas is well in thermodynamic equilibrium. Further, we demonstrate an accurate, calibration-free determination of the gas temperature from the measured spectroscopic data.

Excitation and emission spectra of rubidium in rare-gas thin-films

To understand the optical properties of atoms in solid state matrices, the absorption, excitation, and emission spectra of rubidium doped thin-films of argon, krypton, and xenon were investigated in detail. A two-dimensional spectral analysis extends earlier reports on the excitation and emission properties of rubidium in rare-gas hosts. We found that the doped crystals of krypton and xenon exhibit a simple absorption-emission relation, whereas rubidium in argon showed more complicated spectral structures. Our sample preparation employed in the present work yielded different results for the Ar crystal, but our peak positions were consistent with the prediction based on the linear extrapolation of Xe and Kr data. We also observed a bleaching behavior in rubidium excitation spectra, which suggests a population transfer from one to another spectral feature due to hole-burning. The observed optical response implies that rubidium in rare-gas thin-films is detectable with extremely high sensitivity, possibly down to a single atom level, in low concentration samples.

Preliminary evaluation of experimental techniques for studying the absorption of rubidium by grape roots

Abstract The experimental material consisted of root segments excised from grape cuttings maintained in nutrient culture. In every experiment reported here washed roots absorbed Rb at substantially higher rates than unwashed root segments. The absorption of Rb per unit weight of root was generally in the same low range for unwashed roots with little regard to diameter, age, browning, or the presence of an intact root apex. On the other hand, after washing, uptake was much higher in large diameter roots than smaller ones, higher in white roots than in brown ones, and higher in younger tissues than older ones, The response to washing is markedly reduced by the presence of an intact attached root apex.

Short Report : Effect of amines and guanidines on Rb + absorption by excised corn roots

The effect of alkyl-amines and -guanidines on the absorption of rubidium by the excised roots of the corn plant was tested. Inhibition of Rb + absorption was observed with both amines and guanidines, where guanidines were more effective. The effect of alkylamines on Rb + transport depends on their molecular structure.

The origin of K 2, Rb 2 and Cs 2 triplet 1 3Π g−X 3Σ +u bands in discharge

The absorption and emission spectra of potassium, rubidium and caesium low-pressure discharges have been studied at the far blue wings of resonance D2-lines. The observed diffuse bands were attributed to the 1 3Π g−X 3Σ + u transition. Experiments revealed the recombination 2P + 2S nature of these bands, and the corresponding rate coefficients were obtained. Energies of the higher excited states as well as the X 3Σ + u -state well depths for K 2, Rb 2 and Cs 2 molecules were estimated.

Relationship of fluorescent intensity to ion uptake and elongation rates of soybean roots

The relationship between the fluorescent intensity of individual soybeanGlycine max (L.) Merr.} roots or root segments and their nutrient absorption capacity or elongation rate was investigated. Data are reported for the short-term (30 sec) absorption of rubidium, phosphate, and iron by roots of soybean plants which had been cultured in a soil solution system. Results indicate that the rates of absorption of Fe, was directly related to the fluorescent intensity, with the most rapid absorption per unit of root length or surface area occuring in regions of most intense fluorescence. Elongation rate was positively correlated to the intensity of root fluorescence. These relationships should be useful for estimating root elongation rates in soil systems and for evaluating the distribution of growth rates and nutrient absorption activities within a crop root system.

Laser excitation of excited states of Rb and Cs atoms in an Ar matrix

Absorption and emission spectra of rubidium and cesium trapped in Ar matrices at 10°K are reported. (AIP)

Influence of Salinity on the Absorption of Rubidium by Spartina alterniflora and Distichlis spicata

The effects of NaCl, CaCl2, and MgCl2 on the absorption of Rb by excised roots and intact seedlings of Spartina alterniflora, and of NaCl on Rb absorption by Distichlis spicata, were studied. In both species, the rate of Rb absorption was reduced when the concentration of NaCl in the external solution was equal to or exceeded 10 mM NaCl. The reduction was proportional to the concentration of NaCl. In S. alterniflora the Ca concentration for maximum Rb absorption by excised roots was 2 mM, about 4 times that reported for nonhalophytes. Magnesium at concentrations up to 40 mM was a poor substitute for Ca, as the Mg-mediated Rb absorption was 2-3 times slower than Ca-mediated absorption.

Influence of Mannitol on Absorption and Retention of Rubidium by Excised Corn Roots

Influence of Mannitol on Absorption and Retention of Rubidium by Excised Corn Roots

THE CONTRIBUTION OF MICRO‐ORGANISMS TO THE APPARENT ABSORPTION OF IONS BY ROOTS GROWN UNDER NON‐STERILE CONDITIONS

SummaryMicro‐organisms can make a considerable contribution to the apparent absorption of inorganic nutrients by excised roots. The microbial component of uptake has been studied by comparing the absorption of phosphate and rubidium by seedling roots of barley grown prior to excision under sterile and non‐sterile conditions.Although relative to the quantities taken up by sterile roots more phosphate than rubidium was absorbed by micro‐organisms, for both ions over the range 0.001‐1.0 mM, the relationship between absorption and increasing external concentration followed the kinetics of a first order reversible reaction. No simple kinetic relationship could, however, be derived to describe the uptake of either phosphate or rubidium by the roots.The significance of these findings is considered in the light of the postulate, derived from experiments under non‐sterile conditions, that the absorption of ions by roots is mediated by two distinct‘carrier’mechanisms, one of which dominates at low and the other at high external concentrations. It is concluded that experiments designed to investigate the nature of the uptake process should be carried out under sterile conditions.

Plasmalemma: The Seat of Dual Mechanisms of Ion Absorption in Chlorella pyrenoidosa

Dual mechanisms of absorption of rubidium were demonstrated in a nonvacuolate unicellular alga, Chlorella pyrenoidosa, in both the light and the dark. The two mechanisms were sensitive to metabolic inhibitors. At high concentrations rubidium enhanced the respiration of Chlorella cells. The findings support the conclusion that the mechanisms of rubidium absorption in both the low and high concentration ranges are active processes and reside in the plasmalemma.

Photosynthetic activity of vegetable plants and its horticultural significance

This study was undertaken to elucidate the photosynthetic activity, carbohydrate metabolism, translocation of assimilates and mineral nutrient uptake in young tomato plants at very low carbon dioxide concentrations.Radioisotopes of 14CO2, H332PO4 and 86RbCl were used as tracers under controlled conditions. Photosynthetic rates were also measured with gas exchange method by means of assimilation chambers and an infrared gas analyser.Photosynthetic rate of tomato leaf was linearly proportional to the CO2 concentration within the range from 70 to 300ppm CO2 at three light intensities of 0.07, 0.16 and 0.53 cal•cm-2•min-1. In an atmosphere containing 80ppm CO2, total activity of 14C fixed into the plants dropped to 35 per cent of the normal, and at the same time significant decrease was observed in the translocation of 14C-assimilates from the leaves to the roots.Fairly good amount of 14C-compounds, fixed in the evening and remained in the leaf till next morning, was translocated into the roots under normal photosynthetic conditions. In a CO2-deficient atmosphere, however, a downward translocation of 14C-compounds was slightly restricted and respiratory losses of 14C-compounds were considerably increased in the leaf.Tomato plants placed in an atmosphere containing 60ppm CO2 for 2 hours had lower level of carbohydrates in the leaf and root.A remarkable increase in 32P uptake was found at very low CO2 concentration in the tomato plants which had been illuminated for 6 hours before 32P-treatment. In contrast, the CO2 depletion caused marked decrease in the 32P uptake for the unlighted plants.The uptake of 86Rb was considerably restricted at low CO2 concentration both in the lighted and unlighted plants. The absorption and accumulation of rubidium were highly dependent on the photosynthetic activity in the tomato plants.From these results, the relationship between the translocation of assimilates and the uptake of mineral nutrients was discussed from physiological point of view.

Energy Sources for the Absorption of Rubidium by Chlorella

ZusammcnfassungDie aktive (stoffwechselabängige) Aufnahme von Radiorubidium aus 8.10−5 molarer Lösung durch Chlorella pyrenoidosa wurde in Langzeitversuchen (1–2 Tage) untersucht. Die Annahinc ist, daβ die dafür notwendige Energie in Form von ATP bereitgestellt werden muβ. Es wurde gefunden, daβ Gegenwart von Na‐ Oder Cl‐Ionen für die aktive Rb‐Aufnahme nicht notwendig ist; die Rb‐Pumpe ist also nicht an eine Na‐ Oder Cl‐Pumpe gekoppelt. Vorbeladene Chlorella gibt Rb über längere Zeiten langsam an das Medium ab.Durch Experimente im Licht bzw. Dunkel und in Gegenwart bzw. Abwesenheit von Luft wurde gezeigt, daβ bei 9000 lux die Beleuchtung mehr Energie für die aktive Aufnahme erbringt als die Atmung. Der Ersatz von Luft durch Sauerstoff hat keine Auswirkung. Die Versorgung mit ATP durch Atmung—nicht aber durch (zyklische) Photophosphorylierung—wird durch 5.10−4 M DNP weitgehend unterdrückt. Die aktive Aufnahme ist klein, wenn sie sich nur auf Glykolyse stützt.Gleichzeitige Einwirkung von Licht, Luft (Sauerstoff) und DNP auf Chlorella führt zu irreversibler Schädigung und Ausbleichung der Algen. Sie hören auf, Rb aufzunehmen und verlieren vorher absorbiertes Rb wieder. Gründe für diesen Effekt werden diskutiert.Die aktive Aufnahme von Rb wird durch 5.10−2 M Glukose gefördert, u.z.w. im Licht und im Dunkel, in Luft‐ und in Stickstoffatmosphäre. In dieser Beziehung unterscheidet sich die aktive Rb‐ von der aktiven Bromid‐Aufnahme. Die Förderung durth Glukose wird durch DNP gehemmt, ausgenommen im Dunkel in Stickstoffatmosphäre. In Gegenwart von DNP wird die Rb‐Aufnahme durch 1% CO2 sowohl im Licht als auch im Dunkel stark herabgedrückt.

The Influence of Initial Salt Status on Absorption of Rubidium by Corn Root Segments of Two Stages of Development

VENRICK, DANA M., and RICHARD C. SMITH. (Univ. of Florida, Gainesville.) The influence of initial salt status on absorption of rubidium by corn root segments of two stages of development. Bull. Torrey Bot. Club 94: 501-510. 1967.-Apical and basal root segments (consisting primarily of meristematic and elongated cells, respectively) of 4-day corn seedlings were tested for various characteristics of active transport, both with and without a preliminary exposure to KCl for 24 hours. The tissue was permitted to absorb Rb+ from a 0.1 mM RbCl solution labelled with 86Rb. Labelled ions held by adsorption or present in the apparent free space were removed prior to radioactive assay. The results show that both apical and basal segments displayed the following characteristics of active transport: absorption resulted in high accumulation ratios; the absorbed ions were retained by the tissue in the presence of external KCl solution; K+ in the experimental solution inhibited uptake whereas Na+ did not; lowering the temperature reduced the rate of uptake to such an extent that Q1o values were greater than 2.0. Pretreatment of the seedlings for 24 hours with 1.0 mM KCI resulted in a subsequent reduction in rate of Rb+ absorption by apical segments but had little effect on absorption by basal segments. In both kinds of segments pretreatment with KCI was followed by the same characteristics of active transport of Rb+ described above. These data provide support for the existence of active transport of Rb+ into both apical and basal corn root segments, and they also show that a long exposure to KCl does not prevent subsequelnt active transport of Rb+.

Variation of the atomic absorption of alkali metals in a flame on displacement of the ionization equilibrium by an external electric field

A constant or alternating electric field applied to graphite electrodes affects the absorption of light by alkali metal atoms in a flame and also the emission intensity. The weakening of the atomic absorption of potassium, rubidium, and cesium near the cathode has been studied both over the width (between the electrodes) and over the height (along the electrode and higher). The effect is connected with the fall in the partial pressure of the metal atoms resulting from a shift of the ionization equilibrium to the right.

Foliar Absorption-An Active Uptake Process

Mechanisms of foliar absorption of phosphate and rubidium in primary leaves of bean seedlings were resolved by a newly developed leaf-immersion and leaf-washing technique. Uptake was expressed as “specific absorption,” defined as mμmoles/cm2 leaf X 24 hr from a known concentration of substance in an external solution maintained in a known environment. Criteria for active uptake included time-course analysis, temperature, oxygen, and energy dependence, sensitivity to metabolic inhibitors, accumulation against a concentration gradient, irreversibility, and pH dependence. The results suggest that the over-all process of foliar absorption of rubidium and phosphate by bean leaves, beginning with zero time and extending over a 24-hr period, is metabolic. It is proposed that carriers play an important role in uptake and that they are proteinaceous.

FOLIAR ABSORPTION—AN ACTIVE UPTAKE PROCESS

Mechanisms of foliar absorption of phosphate and rubidium in primary leaves of bean seedlings were resolved by a newly developed leaf‐immersion and leaf‐washing technique. Uptake was expressed as “specific absorption,” defined as mμmoles/cm2 leaf X 24 hr from a known concentration of substance in an external solution maintained in a known environment. Criteria for active uptake included time‐course analysis, temperature, oxygen, and energy dependence, sensitivity to metabolic inhibitors, accumulation against a concentration gradient, irreversibility, and pH dependence. The results suggest that the over‐all process of foliar absorption of rubidium and phosphate by bean leaves, beginning with zero time and extending over a 24‐hr period, is metabolic. It is proposed that carriers play an important role in uptake and that they are proteinaceous.

Absorption of potassium and rubidium from the soil by corn roots

Absorption of potassium and rubidium from the soil by corn roots

Course of Cation Absorption by Plant Tissue

The absorption of rubidium by excised barley roots from solutions containing calcium was a strictly linear function of time for 1 hour and was temperature-sensitive throughout; there was no evidence of an initial nonmetabolic exchange phase of uptake. The rubidium absorbed reached concentrations many times the external concentration without any slackening of the rate of absorption-evidence for a high degree of irreversibility of the overall absorption process. This is discussed in terms of the "enzyme-kinetic" model of ion transport by carriers.

THE ABSORPTION OF POTASSIUM BY BEECH MYGORRHIZA

SummaryThe processes of absorption and loss of potassium, sodium and rubidium by excised mycorrhizas of beech were investigated.The internal potassium content of mycorrhizas was found to be about 70 μg Equiv. per 100 mg of dry tissue. Sodium was present at about one‐tenth of this value.Temperatures above 20°C, oxygen tensions below 3% and low concentrations of metabolic inhibitors cause loss of potassium. The process of potassium loss in low oxygen tensions is very sensitive to temperature.The rates of absorption of potassium, sodium and rubidium are affected by temperature and their optimum temperatures are between 15 and 20°C.The rates of absorption of the alkali metals are oxygen‐sensitive, and that of potassium reaches zero at about 3 % oxygen. Rubidium absorption from isotopically labelled chloride solutions does not cease in low oxygen tensions owing to physical equilibration of the solution with the tissues.Absorption of alkali metals is inhibited by metabolic inhibitors.The rate of absorption of alkali metals by mycorrhizas which have been stored in water for several days is stimulated by a supply of glucose.These experimental results are discussed and it is concluded that absorption of the alkali metals by mycorrhizas is dependent on an oxidatively produced carrier.