Mobile app designer/Ux designer for a mobile app

We are looking for a mobile app designer that can do very professional mobile app mockups and also some user experience work. This job will require a designer who can do wireframes from sketches to design mockups and final design assets that we can now pass on to the coder to complete . We would like to see samples of similar work you have done ...which shows the wireframes work as well as the colour mock up of the app design. The mockup should show the various transition screens of the app ...not just one screen. please we would like to see clean designs and also business like app designs This initial job is for just one app, but we have other apps in the pipeline ...once this goes well