Tailoring of physical properties of RF-sputtered ZnTe films: role of substrate temperature

• Kafi Devi,
• Usha Rani,
• Arun Kumar,
• Divya Gupta and
• Sanjeev Aggarwal

Beilstein J. Nanotechnol. 2025, 16, 333–348, doi:10.3762/bjnano.16.25

• -3600 Plus) equipped with Integrating Sphere Assembly (Model-ISR-603) in the wavelength range of 200–2000 nm (accuracy 1 Å) available at Ion Beam Centre, Kurukshetra University. The photoluminescence (PL) emission spectra of ZnTe/Qz films were recorded using a HORIBA Scientific (Fluorescence 3.5

• ]. The dielectric constant and the dielectric loss of the deposited ZnTe films exhibit a similar pattern and were also found to decrease with increasing substrate temperature (see below). Photoluminescence studies Photoluminescence (PL) studies were carried out to analyse the films’ electronic features

• . The photoluminescence occurs when a material absorbs energy higher than its bandgap. In a semiconductor, this leads to the creation of a large number of electrons and holes in comparison to their equilibrium concentration. These generated charge carriers recombine after thermal relaxation, and photons

Fabrication of hafnium-based nanoparticles and nanostructures using picosecond laser ablation

• Abhishek Das,
• Mangababu Akkanaboina,
• Jagannath Rathod,
• R. Sai Prasad Goud,
• Kanaka Ravi Kumar,
• Raghu C. Reddy,
• Ratheesh Ravendran,
• Katia Vutova,
• S. V. S. Nageswara Rao and
• Venugopal Rao Soma

Beilstein J. Nanotechnol. 2024, 15, 1639–1653, doi:10.3762/bjnano.15.129

• morphology was analysed using field-emission scanning electron microscopy (FESEM); the composition was determined by EDX attached to the FESEM (Carl Zeiss Smart SEM ULTRA 55). Reflectivity was investigated using a UV–vis–NIR spectrometer (PerkinElmer Lambda 750). For photoluminescence (PL) measurements, a

Heterogeneous reactions in a HFCVD reactor: simulation using a 2D model

• Xochitl Aleyda Morán Martínez,
• José Alberto Luna López,
• Zaira Jocelyn Hernández Simón,
• Gabriel Omar Mendoza Conde,
• José Álvaro David Hernández de Luz and
• Godofredo García Salgado

Beilstein J. Nanotechnol. 2024, 15, 1627–1638, doi:10.3762/bjnano.15.128

• ratio x = [O]/[Si], which is determined by controlling key parameters in the deposition process [2]. This ratio determines optical and electrical properties such as bandgap energy, absorption coefficient, photoluminescence, refractive index, and electrical conductivity [3]. SiOx cannot only be obtained

• exhibited greater photoluminescence compared to those that did not undergo thermal treatment [29]. The SiO species plays an important role in the proposed mechanism; the reaction of SiO with •OH and •H radicals leads to the formation of HSiO and silanes [15]. Silane and silanol species were also found in

Various CVD-grown ZnO nanostructures for nanodevices and interdisciplinary applications

• The-Long Phan,
• Le Viet Cuong,
• Vu Dinh Lam and
• Ngoc Toan Dang

Beilstein J. Nanotechnol. 2024, 15, 1390–1399, doi:10.3762/bjnano.15.112

• . Depending on the morphology and crystal quality, their photoluminescence spectra have only a strong UV emission associated with the exciton radiative recombination, or both UV and defect-related visible emissions with their relative intensity ratio varying with the excitation power density. The obtained

Out-of-plane polarization induces a picosecond photoresponse in rhombohedral stacked bilayer WSe₂

• Guixian Liu,
• Yufan Wang,
• Zhoujuan Xu,
• Zhouxiaosong Zeng,
• Lanyu Huang,
• Cuihuan Ge and
• Xiao Wang

Beilstein J. Nanotechnol. 2024, 15, 1362–1368, doi:10.3762/bjnano.15.109

• contrast, and characterized by photoluminescence (PL) measurements at room temperature (see Supporting Information File 1, Figure S3). The relative angles between crystalline axes of the top and bottom WSe2 layers were determined by polarization-resolved SHG measurements. The zigzag directions of the two

Mn-doped ZnO nanopowders prepared by sol–gel and microwave-assisted sol–gel methods and their photocatalytic properties

• Cristina Maria Vlăduț,
• Crina Anastasescu,
• Silviu Preda,
• Oana Catalina Mocioiu,
• Simona Petrescu,
• Jeanina Pandele-Cusu,
• Dana Culita,
• Veronica Bratan,
• Ioan Balint and
• Maria Zaharescu

Beilstein J. Nanotechnol. 2024, 15, 1283–1296, doi:10.3762/bjnano.15.104

• and MW ZnO samples, with larger Eg values than those of the manganese-doped samples. Photoluminescence Photoluminescence (PL) measurements are usually used to describe the radiative recombinations of electron–hole pairs in semiconductors exposed to light irradiation. A high PL signal measured for a

• catalyst is generally associated with low photocatalytic activity. Accordingly, various modifiers of semiconductor nanomaterials are used to enhance separation of the photogenerated charges, causing a corresponding decrease of PL emission. The correlation between photoluminescence and photocatalytic

• use in photocatalysis processes (i.e., degradation of oxalic acid). In addition, the measured excitonic PL indicates the need for deeper investigation on the ability of the investigated materials to generate reactive oxygen species (ROS) under light irradiation. The photoluminescence signal of the

Realizing active targeting in cancer nanomedicine with ultrasmall nanoparticles

• André F. Lima,
• Giselle Z. Justo and
• Alioscka A. Sousa

Beilstein J. Nanotechnol. 2024, 15, 1208–1226, doi:10.3762/bjnano.15.98

• by biocompatible cyclodextrin with a core size of 1.85 nm [147]. These particles exhibited strong photoluminescence upon excitation at 808 nm, with an emission peak at 1050 nm. Photoluminescence imaging in the second NIR window (1000 to 1700 nm) is advantageous for in vivo deep-tissue imaging as it

• tumor accumulation of the targeted AuNCs reached ≈12% ID, marking a fourfold increase over the control group. Photoluminescence imaging effectively visualized the tumor sites in mice, yielding a ≈3-fold enhancement in emission signal intensity relative to the control animals. 6 Clinical applications of

Green synthesis of biomass-derived carbon quantum dots for photocatalytic degradation of methylene blue

• Dalia Chávez-García,
• Mario Guzman,
• Viridiana Sanchez and
• Rubén D. Cadena-Nava

Beilstein J. Nanotechnol. 2024, 15, 755–766, doi:10.3762/bjnano.15.63

• photoluminescence spectroscopy (PL). The utilization of biomass as a carbon source offers great opportunities due to its abundance in nature and the wide range of sources available, which exhibit good luminescent and catalytic properties. Focusing on the hydrothermal synthesis method using biomass-derived

• Jobin Yvon Xplora Raman microscope using a 532 nm laser excitation as the power source. The photoluminescence spectra of the samples were obtained with an Agilent Cary Eclipse fluorescence spectrophotometer. It consists of two Czerny–Turner slits (excitation and emission) with a double monochromator and

• ) which promotes the inclusion of heteroatoms into the CQDs. All the prepared CQDs samples presented an intensity ratio (ID/IG) around 1.0, which corresponds to a poor crystallinity in the CQDs and, as a consequence, a high relative content of defects. Photoluminescence spectra Investigating the

Simultaneous electrochemical determination of uric acid and hypoxanthine at a TiO₂/graphene quantum dot-modified electrode

• Vu Ngoc Hoang,
• Dang Thi Ngoc Hoa,
• Nguyen Quang Man,
• Le Vu Truong Son,
• Le Van Thanh Son,
• Vo Thang Nguyen,
• Le Thi Hong Phong,
• Ly Hoang Diem,
• Kieu Chan Ly,
• Ho Sy Thang and
• Dinh Quang Khieu

Beilstein J. Nanotechnol. 2024, 15, 719–732, doi:10.3762/bjnano.15.60

• composite (TiO2/GQDs) obtained by in situ synthesis of GQDs, derived from coffee grounds, and peroxo titanium complexes was used as electrode modifier in the simultaneous electrochemical determination of uric acid and hypoxanthine. The TiO2/GQDs material was characterized by photoluminescence, X-ray

• microscope (SEM), Hitachi (Japan). UV–vis absorption spectroscopy measurements was carried out on an 8453 UV–vis spectrophotometer, Agilent, USA. Photoluminescence (PL) spectroscopy measurements were performed on a FL3C-22 spectrophotometer, Horiba, USA. Synthesis of TiO2/GQDs Peroxo titanium complexes were

• capability of the nanomaterials. Low LODs, high reproducibility, and simple procedures for surface modification and analysis can be considered as the advantages of the proposed DPV method. Images of aqueous suspension of TiO2/GQDs samples (a) under white light and (b) under UV light. (c) Photoluminescence

Elastic modulus of β-Ga₂O₃ nanowires measured by resonance and three-point bending techniques

• Annamarija Trausa,
• Sven Oras,
• Sergei Vlassov,
• Mikk Antsov,
• Tauno Tiirats,
• Andreas Kyritsakis,
• Boris Polyakov and
• Edgars Butanovs

Beilstein J. Nanotechnol. 2024, 15, 704–712, doi:10.3762/bjnano.15.58

• the average bond length and thus result in a reduction in the elastic modulus [31][32][33]. For example, Wang et al. [34] showed that ZnO NWs with a higher density of oxygen vacancies, inferred from photoluminescence measurements, exhibited significantly (up to 20%) lower Young’s modulus. Wang et al

• . [35] measured a lower (up to 16%) elastic modulus for Al2O3 NBs in comparison to the theoretical value and attributed this difference to oxygen vacancies within NBs. As per our previous study [36], our as-grown Ga2O3 NWs exhibit a strong photoluminescence band related to oxygen vacancies, indicating a

• thus anisotropy in mechanical properties, are the most probable causes of the significant data scattering of the measured elastic moduli, the reason for the considerable decrease in comparison to the bulk value remains unclear. Our previous study of the as-grown Ga2O3 NW photoluminescence [36] implied

Aero-ZnS prepared by physical vapor transport on three-dimensional networks of sacrificial ZnO microtetrapods

• Veaceslav Ursaki,
• Tudor Braniste,
• Victor Zalamai,
• Emil Rusu,
• Vladimir Ciobanu,
• Vadim Morari,
• Daniel Podgornii,
• Pier Carlo Ricci,
• Rainer Adelung and
• Ion Tiginyanu

Beilstein J. Nanotechnol. 2024, 15, 490–499, doi:10.3762/bjnano.15.44

• produced material is investigated by scanning electron microscopy (SEM), while its crystalline and optical qualities are assessed by X-ray diffraction (XRD) analysis and photoluminescence (PL) spectroscopy, respectively. We demonstrate possibilities for controlling the composition and the crystallographic

• recombination [35]. Therefore, the photoluminescence properties of the prepared aero-ZnS materials, including the near-bandgap emission, are similar to those inherent to semiconductor ZnS single crystals. The PL band around 2.4 eV is also excited by intraband-energy radiation with a wavelength of 405 nm (3.06

• impurities are present in the photoluminescence spectra, including those associated with surface states. Taking into account that, according to previous reports, the surface states, including those related to oxygen species adsorbed at the aeromaterial surface, play an important role in photocatalytic

Photocatalytic degradation of methylene blue under visible light by cobalt ferrite nanoparticles/graphene quantum dots

• Vo Chau Ngoc Anh,
• Le Thi Thanh Nhi,
• Le Thi Kim Dung,
• Dang Thi Ngoc Hoa,
• Nguyen Truong Son,
• Nguyen Thi Thao Uyen,
• Nguyen Ngoc Uyen Thu,
• Le Van Thanh Son,
• Le Trung Hieu,
• Tran Ngoc Tuyen and
• Dinh Quang Khieu

Beilstein J. Nanotechnol. 2024, 15, 475–489, doi:10.3762/bjnano.15.43

• electron microscopy, transmission electron microscopy, ultraviolet–visible diffuse reflectance spectroscopy, Fourier-transform infrared spectroscopy, photoluminescence spectroscopy, vibrating-sample magnetometry, and nitrogen adsorption/desorption isotherms. Cobalt ferrite crystals of around 8–10 nm and

• degradation and other dyes. Keywords: cobalt ferrite; graphene quantum dots; methylene blue; Introduction Graphene quantum dots (GQDs) have unique properties, including photoluminescence, biocompatibility, slight chemical toxicity, inertness, and excellent photostability [1][2]. Graphene quantum dots

• ) and ultraviolet light (254 nm, right); (b) photoluminescence excitation (PL) and photoluminescence emission spectra (PLE) of the GQDs; (c) XRD pattern of GQDs; (d) PL spectra of supernatants from prepared CF/GQD suspensions. (a) FTIR spectra of CF/GQDs and CoFe2O4; (b, c) Raman spectra; (d) TG/dTG

Investigating ripple pattern formation and damage profiles in Si and Ge induced by 100 keV Ar⁺ ion beam: a comparative study

• Indra Sulania,
• Harpreet Sondhi,
• Tanuj Kumar,
• Sunil Ojha,
• G R Umapathy,
• Ambuj Mishra,
• Ambuj Tripathi,
• Richa Krishna,
• Devesh Kumar Avasthi and
• Yogendra Kumar Mishra

Beilstein J. Nanotechnol. 2024, 15, 367–375, doi:10.3762/bjnano.15.33

• photoluminescence spectroscopy. Stupp et al. [14] have explored possible applications of self-assembly of biomolecules with controlled stereochemistry in materials technology. However, the fundamental reasoning behind how this self-organization process evolves in terms of defect creation or damage still needs to be

Determining by Raman spectroscopy the average thickness and N-layer-specific surface coverages of MoS₂ thin films with domains much smaller than the laser spot size

• Felipe Wasem Klein,
• Jean-Roch Huntzinger,
• Vincent Astié,
• Damien Voiry,
• Romain Parret,
• Houssine Makhlouf,
• Sandrine Juillaguet,
• Jean-Manuel Decams,
• Sylvie Contreras,
• Périne Landois,
• Ahmed-Azmi Zahab,
• Jean-Louis Sauvajol and
• Matthieu Paillet

Beilstein J. Nanotechnol. 2024, 15, 279–296, doi:10.3762/bjnano.15.26

• transition to a direct bandgap semiconductor with very high photoluminescence quantum yield when thinned down to a monolayer [13][14][15][16][17]. Its unique electronic and optical properties could provide an edge in many future applications. The multilayers MoS2 structures are of the most common 2Hc type

• growth of wafer-scale MoS2 thin films on SiO2/Si substrates by direct liquid injection pulsed-pressure chemical vapor deposition (DLI-PP-CVD) using low-toxicity precursors [27]. Such MoS2 thin films showed good stoichiometry (Mo/S = 1.94–1.95) and the potential for high photoluminescence quantum yield

• signal in the wavelength range of photoluminescence emission (around 650 nm). The third parameter to define is the power of the 532 nm light, Pλ, impinging the sample. Much of the Raman information available to evaluate the thickness of MoS2 flakes is based on the following parameters: (i) on precise

CdSe/ZnS quantum dots as a booster in the active layer of distributed ternary organic photovoltaics

• Gabriela Lewińska,
• Piotr Jeleń,
• Zofia Kucia,
• Maciej Sitarz,
• Łukasz Walczak,
• Bartłomiej Szafraniak,
• Jerzy Sanetra and
• Konstanty W. Marszalek

Beilstein J. Nanotechnol. 2024, 15, 144–156, doi:10.3762/bjnano.15.14

• [39][40]. One of the main existing challenges in synthesizing QDs is to increase their photoluminescence efficiency while simultaneously shifting the photoluminescence maximum to longer wavelengths. Initial applications focused on OLEDs. CdSe/ZnS quantum dots are luminescent inorganic nanostructures

• ultraviolet with a small exponentially decreasing band up to 500–600 nm (Figure 2). The absorption band maximum is about 260 nm in the solid state (quartz was used as reference) and 330 nm in chloroform solution. The photoluminescence spectra, excited by a 405 nm laser, are shown in Figure 3. This type of

• P3HT:PC71BM:QDs (ratio 1:0.5:0.5) measured in solution. In the case of absorption, spectrum shape and absorption range remain unchanged. The addition of quantum dots slightly increases the intensity in the range from 350 to 550 nm compared to the base P3HT:PC71BM array. In the case of photoluminescence spectra

In situ optical sub-wavelength thickness control of porous anodic aluminum oxide

• Aleksandrs Dutovs,
• Raimonds Popļausks,
• Oskars Putāns,
• Vladislavs Perkanuks,
• Aušrinė Jurkevičiūtė,
• Tomas Tamulevičius,
• Uldis Malinovskis,
• Iryna Olyshevets,
• Donats Erts and
• Juris Prikulis

Beilstein J. Nanotechnol. 2024, 15, 126–133, doi:10.3762/bjnano.15.12

• ] and optical sensors [4][5], require precise control of PAAO layer thickness in the optical sub-wavelength range. Among other examples, by tuning the thickness of PAAO between 200 and 600 nm, it becomes possible to selectively enhance or suppress photoluminescence (PL) bands originating from defects in

• absorption and photoluminescence characteristics of PAAO [38]. In order to achieve nanometer-scale thickness uniformity of the PAAO layers (Figure 4), it was necessary to use single-crystal aluminum substrates as starting material. In previous studies it was shown that anodization of polycrystalline aluminum

Dual-heterodyne Kelvin probe force microscopy

• Benjamin Grévin,
• Fatima Husainy,
• Dmitry Aldakov and
• Cyril Aumaître

Beilstein J. Nanotechnol. 2023, 14, 1068–1084, doi:10.3762/bjnano.14.88

Nanoarchitectonics of photothermal materials to enhance the sensitivity of lateral flow assays

• Elangovan Sarathkumar,
• Rajasekharan S. Anjana and
• Ramapurath S. Jayasree

Beilstein J. Nanotechnol. 2023, 14, 988–1003, doi:10.3762/bjnano.14.82

• ]. NIR light irradiation for 10 min can yield temperatures up to 61 °C in mesoporous PDA with a photoconversion efficiency of 26.7%. Despite the advantages, many of the polymer nanoparticles show strong photoluminescence and do not withstand long-term light irradiation. To overcome this challenge, hybrid

Isolation of cubic Si₃P₄ in the form of nanocrystals

• Polina K. Nikiforova,
• Sergei S. Bubenov,
• Vadim B. Platonov,
• Andrey S. Kumskov,
• Nikolay N. Kononov,
• Tatyana A. Kuznetsova and
• Sergey G. Dorofeev

Beilstein J. Nanotechnol. 2023, 14, 971–979, doi:10.3762/bjnano.14.80

• spectra of the samples SP550, SP670, and SP900 are shown in Figure 3 (SP400 exhibited photoluminescence of an organic origin that hindered Raman studies). The spectra consist of multiple bands that provide a stark contrast to the zinc blende SiP structure, which exhibits a singular Raman mode (with a LO

A graphene quantum dots–glassy carbon electrode-based electrochemical sensor for monitoring malathion

• Sanju Tanwar,
• Aditi Sharma and
• Dhirendra Mathur

Beilstein J. Nanotechnol. 2023, 14, 701–710, doi:10.3762/bjnano.14.56

• hydrothermal process with glucose as a precursor undergoing carbonization. Different spectroscopic techniques were used to analyze the optical characteristics of GQDs, including UV–visible, photoluminescence, FTIR, and Raman spectroscopy. Atomic force microscopy, transmission electron microscopy, and X-ray

• was excited at 320 nm, the photoluminescence (PL) spectrum of GQDs showed a strong peak around 425 nm, similar to those reported for GQDs [32]. When excited at wavelengths between 320 and 420 nm, the PL peak shifts from 420 nm (violet) to 520 nm (green), and the PL intensity also decreases

• -based nanosensor described here could be used in future to develop portable monitoring systems for water contamination. Fabrication of the GQDs/GCE electrochemical nanosensor for the detection of malathion. (a) UV–vis absorption spectrum and (b) photoluminescence spectra of GQDs. (a) TEM image, (b) size

Metal-organic framework-based nanomaterials as opto-electrochemical sensors for the detection of antibiotics and hormones: A review

• Akeem Adeyemi Oladipo,
• Saba Derakhshan Oskouei and
• Mustafa Gazi

Beilstein J. Nanotechnol. 2023, 14, 631–673, doi:10.3762/bjnano.14.52

• excitation, for photoluminescence to occur, whether it be fluorescence or phosphorescence. The molecule-bound electron in the fluorescence mechanism absorbs a photon and is activated after the analyte interacts with the molecular recognition element. The transition from the ground state (S0) to the excited

Titania nanoparticles for photocatalytic degradation of ethanol under simulated solar light

• Evghenii Goncearenco,
• Iuliana P. Morjan,
• Claudiu Teodor Fleaca,
• Florian Dumitrache,
• Elena Dutu,
• Monica Scarisoreanu,
• Valentin Serban Teodorescu,
• Alexandra Sandulescu,
• Crina Anastasescu and
• Ioan Balint

Beilstein J. Nanotechnol. 2023, 14, 616–630, doi:10.3762/bjnano.14.51

• transmission electron microscopy. Also, specific surface area and photoluminescence with optical absorbance were evaluated. By varying the synthesis parameters (especially the working pressure), different TiO2 nanopowders were obtained, whose photodegradation properties were tested compared to a commercial

• transitions, the values obtained in our powders are smaller. A possible explanation is the smaller volume of the particles with anatase crystal structure or the formation of shallow donor levels near the conduction band [64][65]. Photoluminescence (PL) spectra at 260 nm excitation wavelength are presented in

• using a JEM ARM 200F analytical microscope (Jeol, Japan). The specific surface area was measured using a BET flowing gas surface area analyzer, Horiba SA-9600, with a 30% N2/70% He gas mixture. Photoluminescence measurements were carried out using a Horiba Flourolog-3. The excitation source was a xenon

Conjugated photothermal materials and structure design for solar steam generation

• Chia-Yang Lin and
• Tsuyoshi Michinobu

Beilstein J. Nanotechnol. 2023, 14, 454–466, doi:10.3762/bjnano.14.36

• photophysical properties and hydrophobicity through organic reactions. In general, DPP dyes have high photoluminescence quantum yields, but they have a relatively low photostability, degrading after 150 min under a collimated 300 W Xe lamp light source. It was previously reported that introducing electron

• -INCN (Figure 4b and Figure 4c). This suggests that stronger EW end groups and longer conjugation lengths induce more potent ICTs for the DPP derivatives, resulting in smaller bandgaps. In the photoluminescence (PL) spectra of the DPP derivatives, DPP-DCV displayed a much weaker PL than DPP-H, and no PL

• THF solution and (c) for drop-cast films. (d) The photoluminescence (PL) spectra of the DPP derivatives in THF solution. (Figure 4 was adapted with permission from [27], Copyright 2021 American Chemical Society.) Typical polymeric PTMs used for SSG. (a) Schematic illustration of the fabrication

Structural, optical, and bioimaging characterization of carbon quantum dots solvothermally synthesized from o-phenylenediamine

• Zoran M. Marković,
• Milica D. Budimir,
• Martin Danko,
• Dušan D. Milivojević,
• Pavel Kubat,
• Danica Z. Zmejkoski,
• Vladimir B. Pavlović,
• Marija M. Mojsin,
• Milena J. Stevanović and
• Biljana M. Todorović Marković

Beilstein J. Nanotechnol. 2023, 14, 165–174, doi:10.3762/bjnano.14.17

• characterization methods (AFM, TEM, EDS, FTIR, photoluminescence, and EPR) indicate the significant influence of the precursor on structural, chemical, and optical properties. Antibacterial and cytotoxicity tests showed that these dots did not have any antibacterial potential, because of the low extent of reactive

• resistance, and better antioxidant properties compared to pristine CQDs [5]. Functionalization of CQDs with amino groups (NH2 groups) induces a redshift of the photoluminescence because of the charge transfer from the amino groups to the carbon honeycomb core [6]. Also, grafting with NH2 groups, by means of

• . Photoluminescence of CQDs can be tuned, and quantum dots emit light in the range from blue to red. Some of them have very good prooxidant and antioxidant properties [14]. Under blue light irradiation, CQDs produce reactive oxygen species (ROS), which cause oxidative stress and further bacterial death [17][18][19

Formation of nanoflowers: Au and Ni silicide cores surrounded by SiO_x branches

• Feitao Li,
• Siyao Wan,
• Dong Wang and
• Peter Schaaf

Beilstein J. Nanotechnol. 2023, 14, 133–140, doi:10.3762/bjnano.14.14

• and surrounding SiOx nanowires (NWs) show a significant enhancement of the photoluminescence (PL) emission compared with pure SiOx NWs due to the coupling effect between the local surface plasmon resonance (LSPR) of Au nanoparticles and the PL emission of SiOx [2]. Similar Au–SiOx nanoflowers have